Abstract:CRISPR-Cas系统是在原核微生物中广泛存在的抵抗病毒(或质粒)入侵的防御系统。基于CRISPR-Cas9系统发展的基因组编辑工具可以方便快捷地实现对生物体内基因组的精确编辑，如突变基因的修复、有益基因的强化和有害基因的删除等，已在生命科学基础研究、经济物种遗传改良和人类医药健康等领域获得广泛应用，其主要发明人Emmanuelle Charpentier和Jennifer A. Doudna教授于2020年荣获"诺贝尔化学奖"。CRISPR-Cas9基因组编辑技术在深刻改变生命科学与医学领域研究范式的同时，也提示丰富多彩的微生物资源依然是颠覆性生物技术创新的源泉，微生物前沿基础研究具有极其重要的战略意义。

Abstract:[Background] The global redox-sensing transcriptional regulator Rex (encoded by the ydiH gene) of Bacillus subtilis can regulate intracellular redox balance by sensing NADH/NAD+ levels. [Objective] To study the effect of Rex on the synthesis of acetoin through regulation of cofactor pools in B. subtilis. [Methods] RNA-seq was used to identify the transcriptional diversity of genes that were involved in the bioprocess of reversible transformation between acetoin and 2,3-butanediol, and ydiH, acuA (acetyl AcsA) and acoC (dihydrolipoamide acetyltransferase) were knocked out by Cre/lox gene knockout technology. Subsequently, the transcriptional levels of acetoin-related genes in the knockout strains was analyzed by real-time fluorescence quantitative PCR (RT-qPCR). [Results] Fermentation results indicated that blocking of ydiH could inhibit biomass of B. subtilis to a certain extent, but acetoin yield of unit cell and substrate conversion rate were significantly increased in early stage of fermentation. However, knockout of acuA and acoC had little effect on acetoin synthesis, biomass and glucose consumption rate. After knocking out ydiH, the transcriptional levels of alsR (positive transcriptional regulator of alsSD), alsS (α-acetolactate synthase), alsD (α-acetolactate decarboxylase) and bdhA (2,3-butanediol dehydrogenase), involved in acetoin synthesis, were significantly up-regulated. [Conclusion] Global redox-sensing transcriptional regulator Rex in B. subtilis affect the synthesis of acetoin by down regulation of the transcription levels of acetoin synthesis related genes. This study first reported the correlation between Rex and the synthesis of acetoin in B. subtilis, laying the foundation for exploring how Rex affects intracellular redox balance by regulating the transcription of related genes, and providing reference for improving the industrial production intensity and substrate conversion rate of B. subtilis.

Abstract:[Background] Yeasts are the most important microbes in Maotai-flavor Baijiu production. However, the structures and functions of core yeasts in the fermentation microbiota are unclear. [Objective] To reveal the fermentation mechanism of the Baijiu-making process and improve the product quality, we illustrated the structures and functions of core yeasts in fermentation microbiota. [Methods] Culture-independent (internal transcribed spacer amplicons and metatranscriptomics sequencing) and culture-dependent (strain selection and simulated fermentation experiments) technologies were used to analyze the structural change of yeast microbiota and function of core yeasts in the fermentation process of Maotai-flavor Baijiu production. [Results] Results of amplicons and metatranscriptomics showed that yeast in the fermentation process classified to 10 genera. We selected 13 core structure species (relative abundance>0.2%) of yeast microbiota and identified 2 core yeasts including Pichia kudriavzevii and Schizosaccharomyces pombe. In the fermentation process, the relative abundance of P. kudriavzevii had more than 89% of the total microbes in the yeast microbiota. Meanwhile, Schi. pombe expressed more than 21% of the total functional genes in the yeast microbiota. Moreover, the results of the simulated fermentation experiments showed that P. kudriavzevii could tolerate lactic acid accumulation and Schi. pombe could tolerate ethanol accumulation in the yeast microbiota. The effects of two core yeasts ensure the stability of Baijiu production during the fermentation process. [Conclusion] P. kudriavzevii and Schi. pombe are the dominant yeasts in the fermentation process of Maotai-flavor Baijiu production. These two yeasts play different roles during fermentation. Our research further deepened our knowledge about the contribution of core yeasts for fermentation process. It also makes researchers recognize the importance of the regulation of core microbes during Baijiu production.

Abstract:[Background] A marine actinomycete strain BM-2 was isolated from coastal area of Lianyungang, Jiangsu province. It showed both antibacterial and growth-promoting effects, and had a good prospect of development and application. [Objective] To clarify the taxonomic status of strain BM-2, reveal its growth-promoting mechanism and provide theoretical basis for its development and application. [Methods] Morphological observation, physiological and biochemical characteristics, combined with 16S rRNA gene sequence analysis were used for the identification of strain BM-2. The phosphorus and potassium solubilities, nitrogen fixing ability and phytase and 1-aminocyclopropane-1-carboxylate (ACC) deaminase activities of strain BM-2 were determined by transparent circle method and plate marking method. The ability of obtained strain to produce indole acetic acid (IAA) and siderophore were measured by Salkowski method, chromeazurol S (CAS) method, respectively. [Results] According to the culture characteristics, colony morphology and physiological and biochemical tests, the strain BM-2 showed a typical feature of Streptomyces. Sequence analysis indicated that the 16S rRNA gene sequence of strain BM-2 had 99.72% sequence homology with Streptomyces badius in GenBank. Strain BM-2 had both nitrogen fixation and organophosphate solubility capacities and had the ability to produce ACC deaminase, siderophore and IAA. [Conclusion] Strain BM-2 was identified as Streptomyces badius. Nitrogen fixation, organophosphate solubilities, ACC deaminase production, siderophore and IAA were the possible mechanism of its growth-promoting effect.

Abstract:[Background] The frequent occurrence of harmful algae blooms causes serious marine ecological problems, which not only directly affects the stability of marine ecosystems, the sustainable use of marine biological resources, and the healthy development of marine aquaculture, but also lead to a serious threat to human health and even life. Efficient algae-lysing bacteria are one of the effective tools to control harmful algae blooms by biological methods. [Objective] Isolation and molecular identification of algae-lysing bacteria with high algicidal effect on Skeletonema costatum, and studying the algae-lysing mechanism of this strain and the characteristics of algae-lysing substances secreted by algae-lysing bacteria. [Methods] The 2216E plate dilution method was used to isolate and purify bacteria. The 16S rRNA gene sequence was determined to identify the bacterial species. The cell concentration was monitored using microscope for both control and treatment to calculate algicidal rate. The algicidal progress of challenged S. costatum was observed by scanning electron microscope. The algae-dissolving process of S. costatum was studied by using conventional physiological and biochemical methods to study the characteristics of algae-lysing substances. The molecular weight of algae-lysing substances was detected by dialysis bag retention method. [Results] A high-efficiency alginolytic bacterium FDHY-CJ for S. costatum was isolated, which belonged to the genus Alteromonas (Alteromonas sp. FDHY-CJ). The 72-hour treatment of red tide algae by this strain showed that the algae lysis rate was 95.45% against S. costatum and less than 40% for other common red tide algae. Algae-lysing FDHY-CJ lyses algae through extracellular secretions. The algae-lysing properties of algae-lysing substances are not affected by repeated freezing and thawing, but are sensitive to acidity, alkalinity and temperature. Scanning electron microscopy observations showed that the algae-lysing bacteria’s algae the substance directly dissolves the cell wall of S. costatum, causing the siliceous shell to open and the contents to flow out, then the algae was lysed. The algae-lysing active substance has the characteristics of being precipitated by ethanol and ethyl acetate. [Conclusion] The algae-lysing bacteria FDHY-CJ has specific algae-lysing effect on S. costatum. The bacterial algae-lysing was indirect algae-dissolving through secretion, and the molecular weight of this compound was between 3.5 kD and 10.0 kD.

Abstract:[Background] Powdery mildew is one of the main fungal disease affecting the yield and quality of alfalfa. It has been reported that there are three pathogens causing alfalfa powdery mildew: Erysiphe polygoni DC., Leveillula leguminosarum Golov., and Erysiphe pisi DC. [Objective] The biological characteristics of alfalfa powdery mildew, the morphological characteristics of conidia and cleistothecium were systematically studied, and the pathogenic species of alfalfa powdery mildew in Ningxia were identified. [Methods] The occurrences of the disease and the formation conditions of the cleistothecia were investigated by pot culture in the laboratory. The data were obtained automatically by the meteorological station. The characteristics of the fungi were observed by the light microscope, and the germination characteristics of the conidia of the fungi were observed by the water agar slide method. [Results] The temperature range of alfalfa powdery mildew is 20?24 °C, the humidity is 40%?60%. The conditions for the formation of cleistothecia are 20?25 °C and humidity about 70%. The formation of cleistothecium takes about 42 d. Conidia produce spores on conidiophore in a basipetal form. Mature conidia oval or elliptic, with the size is (29?46)×(12.5?21.0) μm. The diameter of dark brown globular or subglobular cleistothecium is 71?135 μm, with a large number of appendages, and a few are irregular branches 1?2 times. The cleistothecium contains 4?6 asci, oval, with the handle, and the size is (58?90)×(29?60) μm. The ascus contains 4?6 ascospores, which are ascospore monospora, oval and the size is (21?34)×(10.5?20.0) μm. The optimum temperature range of conidia germination is 22?26 °C, the optimum pH is 6.5, and the light could promote conidia germination. Glucose, D-xylose and mannitol promoted the germination of conidia and the growth of bud tube, cysteine promoted conidia germination, and glycine promoted the growth of bud tube. [Conclusion] The pathogen of alfalfa powdery mildew in Ningxia was identified as Erysiphe polygoni DC.

Abstract:[Background] The growth-promoting effects and mechanisms of Bacillus velezensis and Bacillus firmus on peanut seedlings have not been reported. [Objective] This study comprehensively explored the growth-promoting mechanism of two Bacillus strains on peanut by analyzing of rhizosphere microbial community and soil available nutrients, including nitrogen, phosphorus and potassium. [Methods] two strains (named as Bacillus velezensis HP9, Bacillus firmus HP10) were irrigated-root alone, or mixed on peanut seedling by pot experiment, their effects on peanut’s growth and available nutrients of rhizosphere soil were assessed. The community structure and diversity of bacteria and fungi in rhizosphere soil, including irrigated-root groups and control group, were analyzed by high-throughput sequencing technology, too. [Results] Comparing to control group, stem length and fresh weight of treated peanuts were obviously increased; in rhizosphere soil, alkali-hydrolyzed nitrogen contents was improved greatly, available phosphorus and potassium contents were also increased differently. When Bacillus strains were irrigated with peanut seedlings, there were no significant influence on microbial diversity of rhizosphere soil, but microbial community structure, including bacteria and fungi, were affected. At the phylum level, the relative abundance of Bacteroidetes and Mortierellomycota increased significantly in three treated groups. relative abundance of these genus, such as Agrobacterium, Arthrobacter, Bacillus, Burkholderia, Flavobacterium, Pedobacter, Polaromonas, Pseudomonas, Sphingomonas, Stenotrophomonas, were significantly improved; and six bacterial genus, including Achromobacter, Brevundimonas, Chryseobacterium, Ochrobactrum, Sphingobacterium and Sphingopyxis, were only detected in three treated groups. Using the method of principal component analysis, community structure of rhizosphere soil were found more similar in treated groups than the control. [Conclusion] Bacillus velezensis HP9 and Bacillus firmus HP10 could influence microbial community structure and increase the relative abundance of functional flora in rhizosphere soil, thus the soil fertility was improved and the growth of peanut seedling was promoted, too.

Abstract:[Background] Medicago sativa common leaves spot caused by Pseudopeziza medicaginis is a main fungal disease in M. sativa. This strain can overwinter by the formation of apothecia and then release ascospore to complete primary infection. Thus we observed the fruit body under an electron microscope for exploring the colonization mechanism of P. medicaginis. [Objective] To clarify the conditions of ascospore germination, whether the Ca2+ signal pathway is involved in the form of appressoria and observe the ultrastructure of the ascospore and fruit body of P. medicaginis. [Methods] Effect of different types of carbon and nitrogen sources and the different doses of Ca2+ on ascospore germination and appressoria form were studied by optical microscope. The ultrastructure of the fruit body and ascospore were observed by a transmission electron microscope. [Results] Carbon and nitrogen sources benefited the ascospore germination. Glucose, maltose, sucrose, amino acetic acid, yeast powder, urea, peptone, ammonium nitrate, sodium nitrate and so on could induce the formation of appressorium. Urea had the strongest effect. The Ca2+ not only could promoted the germination of ascospores but also could induce the formation of appressorium, the effect was better than adding carbon and nitrogen sources. With Ca2+ concentration increased, the rate of ascospore germination and the rate of appressoria formation increased, the best dose of Ca2+ was 10 mmol/L, once exceed this dose, the rate of ascospore germination and the rate of appressoria formation decreased. With exogenous Ca2+ or A23187 which is Ca2+ carrier addition, the inhibition role of EGTA could partially relieved. Neomycin, an inhibitor of phospholipase, nicardipine which could block Ca2+ channels, chlorpromazine, CAM antagonist could inhibit the germination of ascospores of this strain. The mature P. medicaginis fruit body broke through the epidermis of the host, and the middle part of the fruit body cracked to expose the ascus. The surface of ascospore had a ring-shaped pattern, the nucleus was dark, the number of organelles such as mitochondria is large, the number of lipids was large and developed, and the cells were filled with high electron density materials. [Conclusion] Ca2+ signal pathway was involved in the process of ascospore germination and charge of the appressoria formation of P. medicaginis.

Abstract:[Background] Silkworm pebrine is a serious disease that has caused great damage to the silkworm production and its pathogen is the unique quarantine object that for silkworm egg production. The sources of pathogenic microsporidan of silkworm B. mori are variety and complex, which increases the difficulty of controlling pebrine in the silkworm egg production. [Objective] The present study were conducted to investigate the pathogenicity and classification feature of a microsporidan which was isolated from the silkworm mother moths (name GXM15), and its source was analysed, which will improve the classification and database of silkworm pathogenic microsporidian and will be provide reference basis for the control of silkworm pebrine in silkworm egg production. [Methods] The 50% infectious concentration (IC50) and the germinative infection rate of GXM15 were investigated with biological test methods. The spore morphology of GXM15 was observed with optical microscope, its internal structure was observed under transmission electron microscope, the SSU rRNA gene and ITS sequence of GXM15 were obtained by PCR amplification, clone and sequencing, the phylogenetic tree based on SSU rRNA sequences was constructed with the software of MEGA 5.0, and the genetic distance of SSU rRNA and ITS sequence were analyzed with software of DNAstar. [Results] The IC50 of GXM15 is 8.29×104 spores/mL, which is 2.28 times to that of Nosema bombycis (Nb) and the germinative infection rate of GXM15 is 3.60%, that is significantly lower than that of Nb. The spore of GXM15 is short oval in shape and (2.05±0.20)× (3.25±0.30) μm in size, and the volume of GXM15 is 2.19 times to that of Nb. There are binuclear and has 13 polar filament coils in the spores of GXM15, and its angles of polar filament is 45°, that is conform to the taxonomic features of Nosema. The SSU rRNA of GXM15 is grouped in the Nosema clade, and the genetic distance analysis of SSU rRNA and ITS show that GXM15 and other Nosema microsporidian are belong to different species of the same genus, GXM15 is a new microsporidian. [Conclusion] GXM15 is a new pathogenic microsporidan of Bombyx mori, and study on the pathogenicity and classification feature of GXM15 microsporidan can provide basis for prevention and control of the silkworm pebrine.

Abstract:[Background] Myxobacteria are a group of higher prokaryotes with social behaviors. They can produce rich, diverse, and novel secondary metabolites with biological activity, and have great research and development value. [Objective] To screen and identify culturable myxobacteria resistant to the pathogen of potato late blight from soil samples and study secondary metabolites of the isolates. [Methods] Myxobacteria were isolated from soil samples by rabbit feces inducing method. The strain resistant to the pathogen of potato late blight was identified by morphological observation and the 16S rRNA gene sequence analysis. Then, the fermentation parameters were studied by the combination of univariate analysis and orthogonal optimization. The stability and antibacterial activity of the active substances in the concentrated fermentation broth were detected by the filter paper method. The active substances were separated by TLC and HPLC, and the components with antibiotic activity were detected by HPLC-MS. The anti-disease effect of the active substances on potato late blight was determined by the in vitro leaf method. [Results] Strain B25-I-3 isolated from the soil sample showed strong antagonistic activity against P. infestans and was identified as Myxococcus fulvus. The antibiotic substances against P. infestans were mainly present in the extracellular matrix. Its optimal fermentation conditions were: shaking speed 180 r/min, inoculum size 10%, incubation temperature 30 °C, incubation time 7 d. The active substances produced by strain B25-I-3 were highly tolerant to the treatment of protease K, ultraviolet and natural light, temperature, and were easily preserved at low temperatures. The antibacterial and antifungal activity analysis showed the active substances exhibited different degrees of antagonism against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Saccharomyces cerevisiae, Rhizoctonia solani, Fusarium oxysporum, Sclerotinia sclerotiorum. The antagonistic components of strain B25-I-3 contained N-(3-amino-2-hydroxypropyl)-N-methylsulfuric diamide and methyl(2R)-2-azido-3-hydroxyl-2-methylpropanoate. The results of disease control on potato leaves showed that the active substances could significantly inhibit the infection of P. infestans on the detached potato leaves of different varieties without harming. [Conclusion] This study provides basic data for the isolation and identification of active substances and the development of biopesticide against potato late blight.

Abstract:[Background] Dickeya zeae causes bacterial soft rot of several important crops such as banana and rice and may cause heavy losses. Canna edulis is resistant to many biotic and abiotic stressors and only a few pests are reported for this plant. Bacterial soft rot of C. edulis caused by D. zeae CE1 was first reported by our research group. [Objective] This study was conducted to sequence the whole genome of D. zeae CE1 and to compare this strain genomically with the other Guangdong strains of this pathogen from banana (strains MS1 and MS2) and rice (strains EC1, EC2 and ZJU1202), in order to explore any genetic differentiation related to the interaction between pathogenic D. zeae bacteria and their hosts. [Methods] The third-generation sequencing combined with next-generation sequencing method was used to construct the complete genome of strain CE1. Next, comparative genomics was adopted to compare the evolutionary relationships and genomic characteristics of strain CE1 with other strains of the pathogen isolated from banana and rice plants. [Results] The complete genome size of CE1 was 4 714 731 bp, with 4 052 coding genes predicted. Similarly with the taxonomic relation between C. edulis and banana, the strains from C. edulis and banana were closely related showing by the phylogenetic tree, but they were notably different from rice strains. The OrthoMCL analysis revealed that the bacterial gene clusters encoding important pathogenic factors such as: bacterial secretion systems, flagellar proteins, extracellular polysaccharides, and the clustered regularly interspaced short palindromic repeats (CRISPR), did not have obvious differences that corresponded to different types of hosts. Further analysis revealed that 80 genes were specific to the C. edulis and banana strains, while 42 genes were specific to the rice strains. According to the functional prediction, two of the gene clusters found in the specific loci of C. edulis and banana strains were related to fatty acid synthase and quorum sensing, respectively. However, more rice strain-specific genes were involved in carbohydrates transport and metabolism compared to the C. edulis and banana strains; in addition, there was a specific gene cluster from rice strains found in the adjacent genomic locus of the CRISPR array. [Conclusion] comparative genomic analysis have determined the phylogenetic relationship among C. edulis strain, banana strains, and rice strains and found several gene loci that might be involved in the interaction between these D. zeae strains and the hosts of different types. It is recommend providing an early warning to growers that crops closely related to banana and rice may be at risk of infection from these important pathogenic bacteria.

Abstract:[Background] human papillomavirus (HPV) infection is closely related to cervical cancer and precancerous lesions. HPV vaccine is an important means to prevent infection, but the distribution of HPV subtypes has obvious regional differences. [Objective] To acquaint with the current situation of cervical HPV infection in women in Western Sichuan Plateau, and to explore the relationship between HPV infection and vaginal microenvironment changes, which could provide guidance for the use of HPV vaccine and the prevention of cervical cancer to them. [Methods] A total of 3 816 women in plateau area of Western Sichuan in 363 Hospital between November 2017 to May 2019, were selected for HPV genotyping, thinprep cytologic test (TCT) and vaginal microenvironment examination at the same time. The infection rate and genotype distribution of HPV were analyzed, and the relationship between high risk HPV (hrHPV) infection and vaginal microenvironment was discussed. [Results] Among 3 816 women in Western Sichuan Plateau, the total infection rate of HPV was 19.81% (756/3 816), and the infection rate of hrHPV was 16.48% (629/3 816). The highest proportion of hrHPV was HPV52, which was 17.20% (135/785), followed by HPV58 (92/11.72%), HPV16 (89/11.34%), HPV53 (88/11.21%) and HPV18 (55/7.01%). Among 415 cases of cervical cytopathy, 101 cases (24.3%) were infected with hrHPV. The top five subtypes were HPV52/58/16/18/31. The top five of high cytopathic hrHPV infections were HPV52/58/18/31/16, and the top seven of low cytopathic hrHPV infections were HPV58/16/56/53/52/68/51 . Among 1 696 cases of vaginal microenvironment changes, the infection rate of hrHPV was 19.16% (325/1 696), which was higher than that of normal vaginal microenvironment (P<0.05). Bacterial vaginitis (BV) was associated with hrHPV infection (P<0.05), while leukocytosis alone, vulvovaginal candidiasis (VVC), trichomonal vaginitis (TV) and mixed infection were not associated with hrHPV infection (P>0.05). [Conclusion] The infection rate of HPV and hrHPV in women living in Western Sichuan Plateau are higher. The top five subtypes of hrHPV are HPV52/58/16/53/18, and the top five subtypes of hrHPV with cervical cytopathy are HPV52/58/16/18/31. 9-Valent Human Papillomavirus Vaccine may be more suitable for the prevention of HPV infection and cervical cancer in this area. HPV53, which is common in this area, may cause cervical cytopathy, but there is no vaccine available. Therefore, HPV53 may be one of the domestic HPV vaccine development targets. Moreover, BV may be associated with hrHPV infection, so BV infection patients might be one of the key points of cervical cancer prevention and control.

Abstract:Indole, also known as 2,3-benzopyrrole, is a typical nitrogen heterocyclic pollutant compound that is widely used in the chemical, pharmaceutical, dye and other industries. Meanwhile, it is a representative microbial metabolite in natural habitats and can be synthesized, transformed and degraded all the time. Besides, indole has a significant effect on various biological functions, such as the formation of microbial biofilms, motility, toxicity, plasmid stability, and even antibiotic resistance of the microbes. Thus, indole has been considered as a new and multifunctional inter-specific and inter-kingdom signaling molecule, playing an important role in bacterial physiology and animal behavior. Therefore, studying the mechanism of indole metabolism mediated by microorganisms as well as elucidating the basis of biological functions might be the key to reveal its fate and ecological significance to natural environment. In this review, the microbial resources and pathways of indole metabolism are systematically summarized. The important functions as signal molecules are also introduced, and the interactions of indoles-microorganisms are illustrated. The review provides important theoretical reference for revealing the metabolic mechanism of indole in complex environments.

Abstract:Bacillus spp. are widely used as a biological agent in the management of diseases in crops, livestock, poultry and aquatic animals. Bacillus velezensis is a novel species of the genus Bacillus. This species produces various secondary metabolites, and shows a broad spectrum of antimicrobial activities, and promotes plants and animal growth. Additionally, it is widely used in the biological control of animal and plant diseases. Here, we review the taxonomic status, methods of identification, antimicrobial substances and related gene clusters, antagonistic mechanism and application of B. velezensis. Industrial and agricultural applications of B. velezensis are elaborated and the existing problems are discussed, to provide a useful reference for the study and application of B. velezensis.

Abstract:Pleurotus geesteranus originated in India and was introduced into Chinese mainland from Taiwan province after domestication. Its taste is delicious, with rich nutritional value and anti-tumor active substances. In recent years, its industrial scale is increasing, and it has a good development prospect. In this paper, the research status and progress of P. geesteranus were reviewed from the aspects of cultivation technology, genetics and breeding, quality and pharmacological function, postharvest preservation and spent mushroom substrate. It will provide reference and theoretical basis for the healthy development of P. geesteranus industry in the future.

Abstract:China has been the largest producer of edible fungi in the world, and produced more than 100 million tons spent mushroom substrates (SMS) every year. These SMS contains a large number of substances such as crude fiber and polysaccharide, but most of them are directly discarded and burned, which causes serious natural environmental pollution and waste of resources, and also does not comply with the policy of Chinese environmental protection in new period. So how to transform waste into treasure, utilizing the SMS scientifically, environmentally, economically and reasonably has become an important link in the healthy development of edible fungi industry. In this study, the main problems in the utilization of SMS are discussed by expounding the way and actuality of comprehensive utilization of SMS. At last, the future direction and development trend of utilization of SMS are prospected, which provides reference and theoretical basis for efficient utilization of SMS.

Abstract:Melanin, a phenolic polymer hydrophobic pigment, produced via the 1,8-dihydroxynaphthalene (DHN) pathway, 3,4-dihydroxyphenylalanine (L-DOPA) pathway or both pathways, is widely distributed in organisms and the DHN melanin mainly exists in the plant pathogenic fungi of ascomycetes. With the development of genomic and transcriptome technologies and the studies of functional genomes, key genes of DHN melanin biosynthesis pathway have been identified in different pathogenic fungi, and the relationship between melanin and fungal resistance, development and pathogenicity has attracted more and more attention. This article reviewed the DHN melanin synthesis pathway and its role in the fungal resistance against radiation and extreme temperature, the influence for fungal infection and development, to deepen the understanding of melanin mediated coevolution of fungi and environment or hosts, which has great importance for the basic research of DHN melanin and its utilization.

Abstract:As a vital spice, vanillin is widely used in diverse industries. Natural vanillin cannot meet the demand of market due to many restrictions. Therefore, chemical synthesis of vanillin is the main source for market. With the continuous depletion of natural resources and the improvement of people’s awareness of environmental protection in recent years, the biological production of vanillin by microbial transformation using suitable substrates has gradually become a research hotspot. This article reviewed the related research progresses on vanillin production by bacteria and fungi with eugenol, isoeugenol and ferulic acid as substrates and also presented the investigation of the metabolic pathways of vanillin produced by eugenol, isoeugenol and ferulic acid as well as the application of biotechnology in this field. The biosynthesis of vanillin heralds vast potentials for development and considerable market prospects.

Abstract:Streptomyces are gram-positive bacteria with complex life cycle, and considered as the most extensive source of natural antibiotics due to the abundant and diverse secondary metabolites. Current studies on Streptomyces mainly focus on the secondary metabolism and morphological differentiation processes. The transport systems of Streptomyces have raised a lot of attention in recent years due to the important roles in these life processes. The transport systems have a great application prospect in the industrial production for their participation in morphological differentiation process through the signal transduction system and delivery of the secondary metabolites. In addition, as the “first door” of bacteria, transport systems can carry nutrients to regulate the primary metabolic processes, further affecting the processes of morphological differentiation and secondary metabolism, resulting in quick adaptation to the complex environment. Therefore, the studies on the transport systems of Streptomyces can provide important guidance for the interpretation of the regulation pathway of morphological differentiation.

Abstract:The chemistry construction of microbial secondary metabolites is complex, and the determination of their absolute configuration is very difficult. In recent years, electronic circular dichroism (ECD) has been used more and more in the determination of absolute configuration due to its advantages of low dosage and high accuracy, and it has become an important method to study the structure of microbial secondary metabolites. In this paper, the application of ECD in the structure of microbial secondary metabolites was reviewed, which laid a foundation for future research.

Abstract:The discovery of nitrite-dependent anaerobic methane oxidation (N-DAMO) process, mediated by functional microorganisms, gives us a new understanding of the natural carbon and nitrogen cycle. This process can simultaneously reduce methane and nitrogen pollution. The reaction mechanism of N-DAMO process and the physiological and biochemical characteristics of the functional bacteria Candidatus Methylomirabilis oxyfera (M. oxyfera) were systematically introduced in this paper. The molecular and microbiological methods for the study of the functional bacteria were overviewed. This paper summarized and analyzed the research reports of M. oxyfera bacteria in different natural habitats. The potential effects of macro environmental factors such as average precipitation, annual average temperature, different natural areas and growth factors, like carbon source, nitrogen source, pH and oxygen content on the structure of functional bacteria community were revealed. The future research direction of the functional bacteria is proposed, which is expected to clarify the N-DAMO process and the ecological function of the functional bacteria in carbon and nitrogen cycle.

Abstract:To cultivate talents with a global outlook, and further improve the quality of university teaching, Southwest University held a Global Immersion Program for the first time in July 2019. Bacterial Pathogenesis, a course in this program, was used as an example to summarize the schedule, pedagogy, outcome and students feedback. The results showed that this program is innovative and can provide high-quality options for students intended to gain interdisciplinary insights via cutting-edge and close to real life knowledge teaching. Both students and teachers highly recognized this program. This practice gave a framework for future better Global Immersion Program.

Abstract:Fermentation engineering is one of the core courses in the field of bioengineering in colleges and universities of science and engineering. It is an applied and practical professional course, and the traditional application of this course has been unable to meet the current needs of college students looking for quality engineering education. With the rapid development of information technology and automatic control technology, multi-level and interdisciplinary “Internet Plus” teaching has become a new mode of talent training in higher education. In this paper, the fermentation engineering practice and virtual simulation pilot laboratory platform takes engineering as a technical means-combining VR technology, information automation control technology, and database and fermentation process controlling through “Internet Plus”; Constructing a “multi-dimensional” engineering laboratory pilot platform with the combination of “virtual reality”, and using it for innovation and exploration toward building quality education and teaching in the Food Fermentation Skills Training Course of fermentation engineering specialty. The results of the preliminary construction and the earlier teaching results show that the construction of the laboratory platform has a clear improvement in the practical ability of the fermentation engineering and related professional students, and has accumulated valuable experience and immeasurable engineering training data for later construction.

Abstract:In order to ensure the teaching quality under the novel coronavirus pneumonia epidemic, the teaching team actively reformed the teaching of Industrial Microbiology course by restructuring the teaching system and teaching process design. On the basis of Superstar Fanya network teaching platform, an intelligent teaching system integrating network classrooms and digital resources was established, and the design and implementation of the teaching process of Industrial Microbiology was restructured. The online teaching assessment model was preliminarily explored, and the effectiveness of teaching reform was also evaluated. The practice indicated that the reformed curriculum teaching was helpful to stimulate students’ learning interest, improve self-learning ability, promote teacher-student interaction, and finally achieve good effects.

Abstract:[Background] Quality control of raw milk is a key part in the production process of dairy products. Salmonella is one of the main pathogenic bacteria that can contaminate raw milk. With the development of biological detection technology, it is of great significance to establish a practical method for rapid detection of Salmonella in raw milk. [Objective] To evaluate practical application effect of rapid Salmonella detection in raw milk by visual loop-mediated isothermal amplification (V-LAMP) and real-time fluorescence loop-mediated isothermal amplification (RF-LAMP), respectively. [Methods] We established the LAMP reaction system and optimized the reaction conditions, then tested and compared the specificity, sensitivity, stability and effectiveness in practical samples detection by using V-LAMP and RF-LAMP methods, respectively. [Results] Through the rapid detection of V-LAMP and RF-LAMP, all Salmonella standard strains were detected positive, while all non-Salmonella standard strains were negative. The limit of detection for the two methods was calculated to 13 CFU/mL. The detection accordance rate of the two methods were both 100%. The results obtained by detecting Salmonella in 10 artificial contaminated samples were highly consistent with the actual results. With respect to the result obtained by conventional detection method in the 73 real samples, the relative specificity of the two methods were respectively 94.12% and 92.65%, the relative sensitivity were respectively 100% and 100%, the relative accuracy were respectively 94.52% and 93.15%, and the χ2 value for consistency analysis were respectively 2.25 and 3.20, showing that no significant difference was found in the results above by the three mentioned methods (P>0.05). [Conclusion] V-LAMP and RF-LAMP methods show good specificity, high sensitivity, and high consistency, which makes them applicable for rapid detection of Salmonella in raw milk.

Abstract:[Background] The subsurface harbors a deep biosphere. It has been investigated that microbial communities inhabit deep environments of sedimentary rocks, basalts, granites and metamorphic rocks. However, microbial characteristics of deep carbonate rock karst-fracture geothermal reservoir is still unclear. Sulfate-reducing bacteria (SRB) are frequently detected in the deep subsurface. [Objective] To develop a droplet digital PCR (ddPCR) technique for rapid and accurate quanti?cation of sulfate-reducing bacteria in deep geothermal water. [Methods] Functional gene dsrB of SRB was used as detection target to optimize annealing temperature of SRB ddPCR technique. Its linear range, sensitivity, repeatability and specificity were examined. Field samples were tested using the technique. [Results] The optimized annealing temperature of SRB ddPCR technique was 54 °C. The linear range of the technique was 1.1×100?1.1×105 copies/μL-DNA with the correlation coefficient (R2) of 0.996. The sensitivity was 1 copy/μL-DNA. All of relative standard deviations (RSD) in the repeatability tests were better than 9%. In addition, no amplification was observed in the templates of 3 non-SRB artificial plasmids. Overall, the technique showed good linear relationship, sensitivity, repeatability and specificity. The technique was applied to quantify SRB in deep geothermal water, shallow water and soil samples collected from the geothermal area located in the middle Hebei Province to obtain an average of (4.0±8.4)×103 copies/mL, (1.6±3.5)×102 copies/mL and (1.5±1.2)×103 copies/g-dw, respectively, showing deep geothermal water was rich in SRB compared with shallow water and soil. [Conclusion] The SRB ddPCR technique was developed to rapidly, accurately and sensitively detect SRB in deep geothermal water for improvement of deep biosphere understanding, scientific development and management of deep geothermal water. At the same time, this technique could contribute to detection of other indicator bacteria in deep geothermal water.

Abstract:[Background] Integron plays important roles in acquisition and spread of antibiotic resistance among bacteria. The research on the improvement of detection methods and reaction mechanisms of integron integration reaction can deepen the understanding of the integron’s contribution in antibiotic resistance acquisition and spread, and provide new ways in suppression of the emergence and spread of the resistant strains. [Objective] To construct class 1 integron reaction model on bacterial chromosome to evaluate integrase-mediated gene cassette site-specific recombination. [Methods] The CM fragment containing chloramphenicol resistance gene cat, the LacA5 fragment containing gene cassette aadA5, the PcS fragment containing integron recombination site attI1 and strong promoter of variable region, the homologous arms on both sides of the knock-in site were amplified by polymerase chain reaction separately. The above five fragments were linked by overlap extension polymerase chain reaction to prepare the knock-in fragment of integron reaction model, and the constructed fragment was knocked into the chromosome of Escherichia coli JM109 by homologous recombination. After transferred with the class 1 integron integrase high expression plasmid pHSint, the integrated strains were screened on streptomycin plate and identified by polymerase chain reaction and sequencing. [Results] The sequencing results of the constructed fragment of integron reaction model were identity with that of expected. The constructed fragment was successfully knocked into the chromosome of E. coli JM109. After transferred with the integrase high expression plasmid pHSint, the strains with gene cassette aadA5 integrated into attI1 were successfully screened on streptomycin plate. The results of polymerase chain reaction and sequencing were identity with that of expected. [Conclusion] Reaction model of class 1 integron integrase-mediated gene cassette site-specific recombination was successfully constructed on E. coli chromosome. It will lay the foundation for further revealing the reaction mechanism of integron capture antibiotic resistance gene cassettes.

Abstract:2020年9月联合国环境规划署发布《全球生物多样性展望-5》(GBO-5)报告，助力世界实现协商一致的愿景——到2050年“与自然和谐相处”。其实，原本地球上的所有生物都是相互依存、互惠共生于地球村的，尽管存在少数“坏分子”。但由于人类的贪婪，过度扩张才导致地球“千疮百孔”的面貌，严重威胁到人类文明可持续发展。通过最近20年的研究，互惠共生微生物(mutualistic symbiotic microbes，MSM)从其丰富的群落多样性到种质新资源、从多种多样的生理生态功能到作用机制、从基础探究到新技术研发，为实现人与自然和谐相处的愿景提供了新机遇，同时也面临新挑战。令人可喜的是，中国在MSM研究领域取得了令世人瞩目的成果。《微生物学通报》于2020年11期特别推出了“互惠共生微生物专栏”，旨在展现中国MSM研究的最新进展和成果，促进生物共生学的发展壮大。

Abstract:[Background] The environmental problem caused by soil heavy metal (HM) contamination upon e-waste dismantling is becoming increasingly serious. Arbuscular mycorrhizal (AM) fungi can colonize plant root and enhance the ability of plant to resist environmental stresses, with important ecological function and application potency. [Objective] To study soil HM contamination effects on the community structure and diversity of AM fungi in e-waste dismantling areas, and to identify AM fungal species which have strong resistance to HM contamination. [Methods] A total of 12 soil samples were collected from a typical e-waste dismantling site and the surrounding areas in Taizhou city, Zhejiang province. The 18S rRNA gene of soil AM fungi was sequenced by pyrosequencing, and the relative abundances of operational taxonomic units (OTUs) and the diversity indices were calculated. [Results] Soil AM fungi in the investigated area are mainly composed by Archaeosporales, Glomerales and Diversisporales, with the dominant order of Glomerales. Although soil AM fungal diversity indices had no significant correlations with the concentrations, and the comprehensive pollution and potential ecological risk indices of HMs, the relative abundance of Rhizophagus vesiculiferus-like OTU positively correlated to all above pollution parameters of HMs. [Conclusion] R. vesiculiferus may have extremely strong resistance to HM contamination, providing technical basis for the treatment of contaminated soil caused by e-waste dismantling in the future.

Abstract:[Background] Parkinson’s disease is a neurodegenerative disorder accompanied by gastrointestinal dysfunction and other non-motor symptoms. Intestinal microflora disorder and increased intestinal epithelial permeability are the main factors that affect the function of intestinal barrier. Dietary restriction can improve the composition of intestinal microflora and maintain intestinal epithelial homeostasis. We hypothesize that dietary restriction might have a protective effect on intestinal barrier function in Parkinson’s disease model mice and the mechanism might be related to the correction of intestinal microflora disorder and the promotion of intestinal tight junction protein expression. [Objective] To investigate the protective effect and its mechanism of alternate day fasting on intestinal barrier in Parkinson’s disease model mice. [Methods] Thirty-two C57BL/6 mice were randomly divided into normal saline+fed libitum group (NS+AL, n=8), normal saline+alternate day fasting group (NS+ADF group, n=8), MPTP+fed libitum group (MPTP+AL group, n=8) and MPTP+alternate day fasting group (MPTP+ADF group, n=8). We took 48 h as an experimental cycle of the alternate day fasting program, with fasting in the first 24 h and free feeding in the second 24 h. We injected 1-methyl-4-phenyl-1,2,3,6-tetrathydropyridine (MPTP) into mice intraperitoneally to build Parkinson’s disease model in the 12th?14th cycles (for five consecutive days) of ADF. After the end of the 17th cycle, we collected the feces of mice and detected the changes of intestinal microflora by high-throughput 16S rRNA gene sequencing, then we detected the behavioral test of mice. After collect jejunum tissues of mice, we observed the histopathological changes of intestine by HE staining. We detected mRNA expression levels of AMPK, Occludin and ZO-1 by RT-qPCR (Prkaa1, Ocln, Tjp1), and detected protein expression levels of ZO-1 by Western blotting in tissue. [Results] The results of behavioral test showed that compared with NS+AL group, the motor ability of mice in MPTP+AL group decreased significantly (P<0.01), while the motor ability of mice in MPTP+ADF group improved (P<0.01). HE staining showed that the jejunum villi in the NS+AL group were structurally completed and closely arranged, while the jejunum villi in the MPTP+AL group were broken or even shed. Compared with the MPTP+AL group, the MPTP+ADF group showed that the jejunum villi were intact and closely arranged. Sequencing results of intestinal microflora showed that the abundance and diversity of intestinal microflora in MPTP+AL group were significantly higher than that in NS+AL group (P<0.001), while there was no significant change between MPTP+AL group and MPTP+ADF group. There were significant differences in intestinal microflora structure between four groups. The relative species abundance at family level showed that compared with NS+AL group, Akkermansiaceae abundance in MPTP+AL group was significantly increased (P<0.05), while in MPTP+ADF group this was significantly decreased (P<0.01). The results of RT-qPCR showed the expression levels of Prkaa1 (P<0.01), Ocln (P<0.01), Tjp1 (P<0.01) were significantly decreased in the MPTP+AL group, while the expression levels of Prkaa1 (P<0.01) and Tjp1 (P<0.01) were significantly increased in the MPTP+ADF group. The expression level of Ocln in the MPTP+ADF group was also higher than the MPTP+AL group, but the difference was not significant. Western blot results showed ZO-1 expression in MPTP+ADF group was significantly higher than that in MPTP+AL group (P<0.05). [Conclusion] Alternate day fasting has protective effect on intestinal barrier in Parkinson’s disease model mice and the mechanism may be related to maintaining the relative abundance at family level of Akkermansiaceae and increasing the expression of intestinal tight junctions.

Abstract:[Background] Arbuscular mycorrhizal fungi (AMF) can promote the nutrient absorption and the growth and development of plants. An invasive plant Wedelia trilobata, invaded in the South China, often distributes in nutrient-poor wasteland, but still grows and expands rapidly. [Objective] To explore whether arbuscular mycorrhizal fungi play an important role in the growth and competition of W. trilobata. [Methods] A greenhouse control experiment was conducted using W. trilobata and its native congener W. chinensis. The effects of AMF (Glomus versiforme), different phosphorus nutrition, monoculture or mix-culture on the growth and the competition abilities of these two plants were investigated. [Results] Both these two plants were infected by AMF, and the colonization percentage of AMF in W. trilobata was significantly higher than that in W. chinensis, especially under low phosphorus. AMF significantly improved the growth and the competition ability of W. trilobata under low phosphorus conditions. [Conclusion] Interactions with AMF not only promote the growth of W. trilobata, but also enhance its competitive advantage. This effect is likely to significantly contribute to the successful invasion of W. trilobata.

Abstract:[Background] As a soil modifier, biochar can improve soil fertility, promote arbuscular mycorrhizal (AM) fungal colonization, plant growth and development. [Objective] To evaluate the effects of AM fungi inoculation with adding biochar on the fertility of continuous cropping soil, and the growth of watermelon plants. [Methods] A pot experiment was conducted with watermelon continuous cropping soil as the substrate for planting ‘Yuanjia’ watermelon (Citrullus lanatus) grafted on the root stock ‘Quannengtiejia’ pumpkin (Cucurbita maxima×C. moschata). A total of 8 treatments were designed with the inoculation with or without AM fungi (Glomus versiforme), being added 0%, 1%, 2% and 4% biochar. The soil physical and chemical properties, soil enzyme activities, soil microbial quantity and the plant growth were measured. [Results] G. versiforme inoculation with biochar addition could significantly promote the formation of large soil aggregates and the mineralization of soil organic matter; stabilize soil pH; increase the number of soil bacteria and actinomycetes, and reduce the number of fungi; increase the activities of soil invertase, hydrogen peroxide enzyme and urease; activate soil mineral nutrients, and ultimately promote the growth and development of watermelon plants. Among them, the effect of inoculating G. versiforme and applying 2%?4% biochar combination is the best. There were interactions between AM fungi and biochar, which improved the continuous cropping soil pH, saturated water content and porosity, reduced the soil bulk density, favorable for the formation of large particles aggregate of soil, increased the soil enzyme activities and improved the rhizosphere soil microbial composition. [Conclusion] The combination of AM fungi and 2%?4% biochar can significantly improve the fertility of continuous cropping soil.

Abstract:[Background] Arbuscular mycorrhizal fungi (AMF) is an important type of soil microorganism that can significantly affect the cadmium (Cd) tolerance and accumulation of plant, but its response to Cd stress of different forms is still unknown. [Objective] In order to investigate the effects of AMF inoculation on the growth and Cd accumulation of maize (Zea mays L.) plants under Cd stress of different forms. [Methods] A culture container with a height of 30 cm filled with quartz sand (0.2 mm) was used for sand-cultivating maize in the indoor experiment. The effects of AMF inoculation with Funneliformis mosseae were investigated on the growth, root morphology, photosynthetic physiology and Cd accumulation of maize seedlings under ionic and colloidal Cd (1 mg/kg) stress. [Results] According to two-way ANOVA results, both the AMF and Cd forms had significant effects on growth (plant height and biomass), root traits, photosynthetic physiology (chlorophyll content and photosynthetic rate) and Cd accumulation in the maize plants. But there was no significant interaction between the AMF and Cd forms. Compared with the non-inoculation treatment, the AMF inoculation significantly decreased the height and biomass, chlorophyll content and photosynthetic rate in leaves, inhibited the root length, root surface area, root volume and root tip number, and increased the Cd content in the roots, but decreased the Cd content in the shoots as well as the Cd accumulation in the shoots and roots of maize. Compared with the colloidal Cd treatment, the ionic Cd significantly decreased the root length, root surface area, average root diameter, root tip number and Cd accumulation in shoots, but increased the photosynthesis rate in leaves, the Cd content and accumulation in the roots of maize. The correlation analysis indicated that the root length, root surface area and root tip number were significantly or extremely positively correlated with the Cd content in shoots, and extremely significantly negatively correlated with the Cd content in roots of maize. [Conclusion] The toxic effect of ionic Cd was more serious than the colloidal Cd on sand-cultured maize seedlings. The AMF inoculation increased the damage of the ionic and colloidal Cd to maize seedlings, but decreased the Cd accumulation of maize.

Abstract:[Background] Gut microbiota is an important part of human body and plays an important role in various life activities. [Objective] To explore the characteristics of gut bacteria community in Uyghur and Han children in order to provide more effective and accurate nutrition intervention strategies for children's nutritional health monitoring and nutrition improvement. [Methods] 20 children of 10?12 years of school age Uyghur and Han nationality were selected from Zepu county and Minquan county, respectively. Collect their fresh feces at the same time period, extracted the total bacterial DNA, through high-throughput sequencing and bioinformatics analysis to study the gut bacteria community differences between healthy Uyghur children and Han children. [Results] 2 007 100 sequences were obtained and classified into 994 OTUs. All the samples contained a total of 15 phyla and 139 genera. Alpha and Beta analyses indicated that there were statistically significant differences in the richness and diversity of gut bacteria in children of the two ethnic groups in the surveyed regions. The richness of gut bacteria community in Uyghur children was higher than that in Han children, while the species diversity was lower than that in Han children. The dominant phyla and genera of Uyghur children's gut bacteria are Bacteroidetes (63%), Firmicutes (22%), Prevotella (61%), Succinivibrio (9%) and Faecalibacterium (5%). While in Han children, the dominant phyla and genera are Firmicutes (57%), Bacteroidetes (23%), Faecalibacterium (16%), Prevotella (11%) and Bacteroides (11%). [Conclusion] The significant differences of gut bacteria community between Uyghur and Han children in the surveyed regions provide a scientific basis for further research on the relationship between gut microbiota, dietary factors and human nutritional health.

Abstract:[Background] Up to now, there was very limited research exploring the symbiotic relationship between bryophytes and arbuscular mycorrhizal fungi (AMF) in temperate desert with the context of snow. [Objective] To reveal the difference of AMF biological diversity in mosses crust layer of desert during the period of early winter (before snowfall), mid-winter (snow-accumulation) and snow melt, we further understand the crucial win-win survival strategy between desert characteristic plants and microorganisms in winter snow accumulation. [Methods] High-throughput sequencing technique was used to study the community composition and diversity of AMF in the dominant bryophyte crusts growing in Gurbantonggut Desert under stable snowfall period, and the difference of AMF community structure before and after snowfall is analyzed. [Results] All operational taxonomic units (OTUs) belonged to 5 orders, 9 families and 11 genera. Of these, these species assigned to the taxonomy of Claroideoglomus, Archaeospora, Paraglomus and Glomus were the dominant groups. There was no significant difference among the dominant genus of AMF in the mosses crust layer between early winter (December) and snow melt (March), and the absolutely dominant genus (>50%) was Claroideoglomus. However, the relative abundance of different AMF groups have different trends between early winter and snow melt. The proportion of Claroideoglomus increased significantly during snow melt period. Compared with early winter, the abundance of AMF assigned to the level of Paraglomus and Glomus decreased. The value of Chao1 index and ACE index used to measure the community richness were in the following order: before snowfall>snow-accumulation>snow melt. It showed that the abundance of AMF community decreased due to snowfall. The visual analysis of taxonomic composition information based on MEGAN software suggested that low abundance AMF groups were more easily affected. Acaulospora was mainly from the samples collected before snowfall, while Diversispora was mainly from the samples collected during the snow melt period. Based on the cluster analysis of genus level communities, it was found that the types of high abundance taxons decreased from 5 before snowfall to 2 after snowfall, which indicated that snowfall had a certain selectivity to AMF groups in bryophyte crusts. The results of principal component analysis (PCA) showed that the characteristics of AMF community structure, including early winter and snow melt, could be effectively distinguished by PCA1. This further verified that the snowfall factors have a significant screening effect on AMF community in the moss crusts. A competitive relationship may exist between the high abundance genus, Claroideoglomus and Glomus, Paraglomus and Archaeospora, due to the negative correlation among them. But because of positively correlated, a cooperative relationship may exist to survive in environment of snowfall between low abundance genus : Gigaspora, Septoglomus, Ambispora and Scutellospora. [Conclusion] The winter snowfall in Gurbantonggut Desert has different selection strategies for the dominant genera and low abundance genera for the AMF group of moss crusts. During the snow melt period, the absolute dominant genus will reduce the proportion of competitive dominant genus, thus further consolidate the dominant position. While the existence of positive correlation of low abundance will synchronously reduce the proportion. Unlike the Tengger Desert, the dominant genus of AMF in the moss crusts is Claroideoglomus but not Glomus in this desert.

Abstract:[Background] Ectomycorrhiza is a symbiosis between ectomycorrhizal fungi and host plant by mycelium infection. It is an important approach for Pinus sylvestris var. mongolica to adapt environmental change and stress. [Objective] To explore a deeply insight on the ectomycorrhizal fungal community composition and diversity in P. sylvestris plantations. [Methods] A chronosequence of plantations (27 years old, 33 years old and 44 years old) were selected in the Mu Us Sandy Land. The community composition of ectomycorrhizal fungi associated with P. sylvestris were identified using the rDNA ITS segment PCR amplification sequencing, and diversity index was calculated. [Results] The 56 obtained OTUs were assigned to 2 phyla, 3 classes, 8 orders, 15 families and 21 genera. The predominant genera were Tomentella, Geopora and Amphinema. The highest richness and alpha diversity index were detected in the 27 and 33 years old plantations, respectively. However, no significance occurred in the three plots (P>0.05). The community composition of ectomycorrhizal fungi was quite different in the plantations affected by the variations in Geopora, Tomentella, Delastria and Mallocybe. [Conclusion] Ectomycorrhizal fungi associated with P. Sylvestris are abundant in the Mu Us Sandy Land. Community composition rather than diversity may indicate the dynamic changes of ectomycorrhizal fungi community with age in the Mu Us Sandy Land. With the sang ageing, the variations in functional ectomycorrhizal fungi potentially contribute to the P. sylvestris plantations degradation. This knowledge gap needs future exploration.

Abstract:[Background] Medicago sativa is excellent leguminous forage that can reciprocate with arbuscular mycorrhizal (AM) fungi and rhizobium. Inoculation of AM fungi and rhizobium can promote soil nitrogen and phosphorus cycling and increase alfalfa yield. [Objective] To study the effects of AM fungi and Rhizobium on the structure and function of rhizosphere bacterial community. [Methods] Rhizosphere and non-rhizosphere soil samples of six different treatment groups were collected, based on the high-throughput sequencing technology of bacterial 16S rRNA gene V3?V4 region. The bacterial diversity and community distribution in the rhizosphere and non-rhizosphere soils of different inoculation treatment groups were analyzed and compared. PICRUSt software was applied to predict the function of bacterial microbiota between different treatment groups. [Results] A total of 3 849 OTU were obtained from 36 soil samples, belonging to 398 species of 50 divisions, 59 classes, 132 orders, 249 families and 595 genera. The main dominant bacteria were Proteobacteria (66.79%, 52.81%?81.46%), Bacteroidetes (7.83%?19.68%) and Actinobacteria (2.21%?16.40%). Compared with no inoculation, the inoculation treatment of Glomus intraradices and G. mosseae increased the beneficial bacteria of Gammaproteobacteria and Bacteroidia, inoculation with Rhizobium increased the abundance of the nitrogen-fixing bacteria Alphaproteobacteria. PICRUSt function prediction analysis indicateed that the bacterial microbiota had a total of 35 sub-functions. Inoculation with rhizobium can increase amino acid metabolism, which is conducive to plant N-nutrient cycle, and inoculation with AM fungi may have a certain inhibitory effect on N-cycle. Compared with single inoculation with AM fungi, double inoculation with AM fungi and rhizobium treatment group had stronger carbohydrate metabolism, which was more beneficial to plant nitrogen and phosphorus cycle. [Conclusion] The inoculation with AM fungi and rhizobium can increase the abundance of different beneficial bacteria related to nitrogen and phosphorus cycle in alfalfa, the results provide a scientific basis for plant nutrient uptake, the increase of alfalfa yield and the development and utilization of bacterial fertilizer.

Abstract:There are a large number of different microbial resources in soil. Soil microorganisms cooperate with most plants in nature, among which arbuscular mycorrhizal fungi (AMF) play an important role. Arbuscular mycorrhizal fungi can form symbiosis with about 90% of plants, providing nutrients for plants by forming arbuscular structures in plants’ roots. Our objective is to understand the effects of AMF inoculation on the tolerance of abiotic stresses of crops during growth (such as drought, extreme temperature, heavy metal pollution, salinity, adverse soil pH changes, etc.). Based on previous studies on the effects of AMF on maize growth under nutrient stress, on the basis of expanding crop varieties, new findings with practical significance were obtained by referring to a large number of literatures, combining with our own experimental research and the latest research progress of predecessors and AMF in recent years. The results are as follows: AMF help plant growth, improve plant nutrition uptake, and protect plants from various environmental stresses. It can be concluded that: AMF use a variety of mechanisms to improve plant growth and crop resistance, create benefits for increased crop yields and farmers’ incomes, and avoid some of the harmful environmental problems caused by excessive fertilizer use. In this paper, the beneficial effects of AMF on plant growth and development under various abiotic environmental stresses (drought, extreme temperature, heavy metal pollution, salinity, adverse soil pH changes, etc.) are reviewed, and different plant responses to mycorrhizal inoculation are summarized. At the same time, some suggestions are provided for the current deficiency and future research.

Abstract:The mutualism between insects and bacteria, which is an ideal model to study the co-evolution between species, is arousing strong interest from biologists in the recent decade. Blochmannia is the primary endosymbiont in Camponotus ants of Formicidae, and represents the earliest described endosymbiosis between animals and bacteria. Blochmannia is essential for supplementing the nutrients lacking in the host diet, and also plays a key role in maintaining the development and growth, reproduction and nutrition metabolism for the host ants. In our paper, the research progress of the localization, maternal transmission, genomics and functions of Blochmannia are reviewed, which hopefully will provide references for the related research.

Abstract:The so-called mutualistic symbiotic microbes (MSM) can colonize other organisms to build a mutual symbiotic system. MSM mainly include mutualistic symbiotic bacteria, mutualistic symbiotic actinomycetes and mutualistic symbiotic fungi. MSM are diverse, with a wide distribution and rich in species diversity, involving those in procaryotae and kingdom fungi. MSM colonize human body, animals, plants, algae, or other fungi, and can build their respective reciprocal symbiotic systems, and then form a wider symbiotic network to play irreplaceable physiological and ecological functions. On the basis of introducing the concept of MSM, this paper summarizes the progress of MSM diversity research, problems existing in the current research, and the work in the future. The results of MSM diversity research are expected to provide basis for the development of MSM application.

Abstract:The diversity of partners in mycorrhizal associations shapes the ecosystem processes and functions. Mycorrhizal fungi and host plants tend to develop in patterns with mutual preference or specificity, which may induce differential benefits to the host plants by diverse fungi, and discrepancies of promotion to the fungi by their plant partners simultaneously. In the process of mutualistic symbiosis, both plants and fungi select their potentially favorable partners and incorporate each other along with facilitative and antagonistic relationships (such as complementarity, selection, and competition), and thus driving the ecosystem development and evolution. This review summarized the mutual effects between mycorrhizal fungal diversity and plant diversity, discussed the presumable regulating factors and the underpinning mechanisms of their correlations, and pinpointed several future research directions based on the concerns in understanding such complicated relationships. Further studies to demystify such interacting relationships between mycorrhizal fungal diversity and plant diversity, will advance our knowledge and understanding on the symbiosis, and also help promote the application of mycorrhizal technologies and sustainability of biodiversity.

Abstract:Frankia spp. can form symbiotic nitrogen fixation with non-leguminous plants such as Hippophae spp., and its nitrogen fixation efficiency is much higher than that of legume rhizobia. Frankia spp. can also promote the resistance of drought and cold and the adaptability of various habitats for Hippophae spp.. Frankia spp. is a kind of actinomycete resources with developmental potential. The progress in Frankia spp. associated with Hippophae were introduced in order to develop and utilize Frankia spp., promote the classification and identification of Frankia spp., strengthen the mechanism of symbiotic nodulation and nitrogen fixation between Frankia spp. and host plants, and develop the application of Frankia spp. in agricultural as soon as possible. This paper reviews the research progress of the species diversity of Hippophae L., the nodulation status and distribution characteristics of Hippophae spp., as well as the morphology and functions of root nodules, the species diversity and distribution characteristics of Frankia spp. The nodulation mechanism of Frankia spp., the physiological and ecological effects of Frankia spp., and the main symbiotic factors of Frankia spp. and Hippophae were discussed. This review can provide valuable reference for systematic research on Frankia spp. associated with Hippophae L.