Abstract:[Background] S-Adenosyl-l-methionine (SAM) is an important intracellular metabolite that can be used as a dietary supplement and to treat a variety of diseases. [Objective] To enhance SAM production for industrial application by blocking SAM consumption pathways in the recombinant Pichia pastoris strain GS115/DS16. [Methods] The genes associated with the metabolism of SAM, sah1 (encoding S-adenosyl-l-homocysteine hydrolase), spe2 (encoding S-adenosylmethionine decarboxylase), and msm1 (encoding mitochondrial methylthio-tRNA synthase), were knocked out in SAM-producing strain GS115/DS16. Accordingly, the engineered strains G/Dsah, G/Dspe, and G/Dmsm were constructed. The cell growth and SAM production of the three engineered strains were investigated. Additionally, the effect of methionine addition on SAM accumulation was studied. [Results] The knock-out did not affect cell growth, whereas it increased SAM production by 29.3%, 55.6%, and 24.8% in G/Dsah, G/Dspe, and G/Dmsm, respectively, compared with the parental strain GS115/DS16. When l-Met addition was decreased from 0.10% to 0.06%, the SAM production increased by 26.4% and 28.9% in G/Dsah and G/Dmsm, respectively. [Conclusion] Therefore, the engineered P. pastoris strains can be utilized in industrial production of SAM in a cost-effective manner, and the strategy can also be employed for improving the production of other chemicals.

Abstract:[Background] Native to Europe, Senecio vulgaris L. (Asteraceae) is widely distributed in southwest and northeast China as well as the high-altitude mountain areas of Hubei Province. In the invasion process, the endophytic bacteria may play a key role in nitrogen and phosphorus. [Objective] To investigate the diversity and functions of endophytic nitrogen-fixing and phosphate-solubilizing bacteria in S. vulgaris and thus to serve as a reference for elucidating the invasion mechanism of this species and controlling its invasion. [Methods] Seeds from six different populations were selected and after germination, seedlings were transferred to pots for growth for 6-8 weeks. Nine healthy plants from each population were picked and the leaf surface and root surface were disinfected. High-throughput sequencing of nifH gene (nitrogen fixation-related gene) was performed to investigate the structure and diversity of nitrogen-fixing bacteria in S. vulgaris. Endophytes were isolated and cultured on Ashby (nitrogen-free) medium and NBRIP (inorganic phosphate) medium, and 16S rRNA gene of the purified nitrogen-fixing and phosphate-solubilizing strains was sequenced. The phosphate-solubilizing ability of the isolated phosphorus-solubilizing strains was determined with the molybdenum-antimony anti-colorimetry method. [Results] The diversity of nitrogen-fixing bacteria in S. vulgaris leaf sample was significantly higher than that in root sample. Among the nitrogen-fixing bacteria, Bradyrhizobium (30.9%−34.0%) was most abundant, followed by Burkholderia (27.2%−27.4%), Methyloversatilis (2.1%−7.1%), and Azospirillum (2.9%−3.9%). A total of 6 nitrogen-fixing phyla were identified and the relative abundance of Proteobacteria was >90% in all samples. A total of 238 isolates (19 genera, 16 families, 10 orders, 7 classes, 4 phyla) were screened out via the Ashby medium. The top genera were Microbacterium (31.0%), Bacillus (24.8%), Pseudomonas (22.1%), Stenotrophomonas (6.2%), and Paenibacillus (2.8%). A total of 318 isolates (16 genera, 15 families, 7 orders, 5 classes, 3 phyla) were cultured on the NBRIP medium, and the top genera were Bacillus (48.4%), Pseudomonas (19.2%), Microbacterium (15.2%), Paenibacillus (3.6%), and Acinetobacter (3.6%). We performed quantitative and qualitative analysis of the phosphate-solubilizing ability of 24 representative strains. The result showed that 17 strains had remarkable phosphate-solubilizing ability and the phosphate-solubilizing process of these bacteria decreased the pH value of the culture medium. [Conclusion] S. vulgaris boasts abundant and diverse endophytic nitrogen-fixing and phosphate-solubilizing bacteria, and the phosphate-solubilizing bacteria may facilitate the invasion of this species.

Abstract:[Background] Early blight is one of the main potato diseases and the pathogen Alternaria has complex species composition and different pathogenicity. [Objective] To clarify the virulence characteristics and functional gene differences of two pathogenic species of potato early blight in Yunnan Province. [Methods] In this study, Alternaria solani (TA-0410) and Alternaria alternata (TB-1129) were collected, isolated, and purified from the main potato production area in Heqing County, Dali Prefecture, Yunnan Province, with the aim of clarifying the virulence characteristics and functional gene differences between the two species through spore morphological observation, pathogenicity verification, whole genome sequencing, and comparative analysis. [Results] TA-0410 was a large-spored species with brown or yellow conidia, spore size of (37.4–151.9(±28.1)) μm×(4.3–22.9(±4.1)) μm, and long beak. TB-1129 was a small-spored species with grayish-brown conidia, spore size of (18.6–42.6(±9.3)) μm× (6.1–15.3(±2.3)) μm, and short beak. The pathogenicity verification showed that TA-0410 was the only pathogenic species, as TB-1129 failed to induce early blight in the case of direct inoculation. However, in the instance of wounded-leaf inoculation, TB-1129 successfully infected the leaves and the lesions were expanded. The genome of TA-0410 was 32.26 Mb, with contig N₅₀=1 158 607 bp, and 177 unique genes, and the genome of TB-1129 was 33.30 Mb, with scaffold N₅₀=2 338 721 bp, and 600 unique genes. In addition, the secretory proteins of TA-0410 were analyzed and 12 candidate secretory proteins containing the RxLx[EDQ] motif were screened out, all of which were annotated as putative proteins. The secretory proteins ASR_2859 and ASR_19579 contained the pathogenic BID_1 and UBA domain, respectively. [Conclusion] Both A. solani and A. alternata can cause potato early blight, with A. alternata only in the case of wounded-leaf inoculation. The phenotypes of the two in the infection and expansion stages are mainly controlled by spore viability and biotoxicity-associated proteins.

Abstract:[Background] Rhizosphere microorganisms directly or indirectly affect the growth, development, and quality of medicinal plants. They improve the physical and chemical properties of soil to increase the diversity of probiotics, promote the biocontrol of plant diseases and insect pests, and improve the plant yield and quality. [Objective] To explore the effects of soil supplementation with hot pepper stalks on the growth quality and rhizosphere bacterial community structure of Polygonatum kingianum. [Methods] The rhizosphere soil samples of P. kingianum were collected from the control field (CK, without any treatment), the field fertilized with decomposed hot pepper stalks (X treatment), and the field fertilized with commercial compound fertilizer (Y treatment). The growth quality of P. kingianum was evaluated, and the bacterial community structure in rhizosphere soil was studied by high-throughput sequencing. [Results] The growth quality of P. kingianum in X treatment was significantly better than that in CK and had no significant difference from that in Y treatment. The polysaccharide content and root activity in X treatment were 24.48% and 56.98%, respectively, higher than those in Y treatment. In addition, the organic matter and soil porosity were also higher in X treatment than in Y treatment. In the rhizosphere bacterial community, Proteobacteria had the highest relative abundance, which was 34.8% in CK, 34.6% in X treatment, and 41.3% in Y treatment, and its relative abundance in Y treatment was significantly higher than that in other treatments. Chloroflexi had the second highest relative abundance, being higher in X treatment (10.2%) than in CK (8.7%) and Y treatment (5.8%). X treatment had significantly higher relative abundance of Cyanobacteria than CK and significantly higher relative abundance of Gemmatimonadetes and Desulfobacteria than Y treatment. The ternary phase diagram (at the genus level) indicated that the genera with the highest relative abundance were Verrucomicrobium and Lysobacter in CK, JG30-KF-AS9 in X treatment, and Pseudomonas and Mitochondria in Y treatment. The α diversity indexes showed no significant difference among treatments. The redundancy analysis showed that organic matter and total porosity were the main factors affecting the changes of bacterial community in X treatment. The cluster of orthologous group (COG) annotation showed that X treatment significantly increased the COGs, with the number of specific COGs (81) significantly higher than that of CK (3) and Y treatment (7). [Conclusion] X treatment improved the growth quality of P. kingianum, changed the structure of rhizosphere bacterial community, and enriched beneficial microorganisms. This study is conducive to the exploration of new functional groups of microorganisms and the research on microorganism-mediated plant response to the environment and microbial synergy under specific environmental conditions. Meanwhile, it gives new insights into the cultivation of P. kingianum.

Abstract:[Background] Arbuscular mycorrhizal (AM) fungi can form mutualistic symbiosis with most plants to promote the growth and enhance the stress resistance of plants, playing an important role in production. However, the immature propagation technology limits the application of AM fungi. [Objective] To establish an efficient propagation system of AM fungi. [Methods] A pot experiment was conducted. Specifically, Rhizophagus intraradice was inoculated into four propagation systems constructed with three host plants (Sorghum bicolor, Zea mays, and Trifolium repens) and five substrates (zeolite, river sand, peat, perlite, and vermiculite) for culture. The effects of different propagation systems on the infection and sporulation of R. intraradice were studied. Then, we measured the infection ability of AM fungi by inoculating S. bicolor with propagation inoculum to verify the propagation effect. Finally, the optimal propagation conditions were employed to explore the propagation of other species of AM fungi: Funneliformis mosseae, Clariodeoglous etunicatum, Diversispora versiformis, and Acaulospora delicate. [Results] The propagation system with river sand+vermiculite+peat (1:4:1) as the substrate and Z. mays+T. repens, R. intraradice as the host plants had the highest spore production of 1 912 spores/g-dry substrate. Moreover, the AM fungi propagated with this system showed better infection potential and remarkably increased the aboveground biomass of S. bicolor. In addition, the propagation with this system increased the sporulation of F. mosseae, C. etunicatum, D. versiformis, and A. delicate by 6.24, 2.92, 35.18, and 4.18 times, respectively, compared with that before propagation. [Conclusion] The propagation system with Z. mays+T. repens as the host plants and river sand+vermiculite+peat (1:4:1) as the substrate had the optimum results. This system had the aeration porosity of 3.57%, the water-holding porosity of 48.19%, the bulk density of 1.03 g/cm³, the electrical conductivity of 152.5 μS/cm, pH 5.61, the available phosphorus of 5.6 mg/kg, the available nitrogen of 80 mg/kg, the available potassium of 449.8 mg/kg, and the organic matter of 56.11 g/kg, which are conducive to the efficient propagation R. intraradice and other AM fungi.

Abstract:[Background] The insect-pathogenic Metarhizium rileyi shows promising potential for controlling the virulent exotic Spodoptera frugiperda which infests crops, particularly maize. Thus, this fungal species should be further developed. [Objective] To optimize the solid-state fermentation conditions of M. rileyi SZCY, determine the virulence of the yielded conidia to S. frugiperda, and thus lay a basis for the large-scale production of the conidia. [Methods] The single-factor experiment and Box-Behnken design were used to optimize the solid-state fermentation medium factors and fermentation parameters. The virulence of the conidia yielded under different conditions to the 3rd instar larvae of S. frugiperda was evaluated. [Results] Husked rice was the best fermentation medium for SZCY, as the conidium yield was the highest. The culture temperature, photoperiod, and content of yeast extract powder were the main factors affecting the sporulation of SZCY in solid-state fermentation. The optimal fermentation parameters for solid-state fermentation are as follows: culture temperature of 22.83 ℃, photoperiod 18.68 h L:5.32 h D, and yeast extract powder of 4.98 g/100 g. Under these conditions, the conidium production of SZCY on husked rice was 5.65×10¹⁰ conidia/g and the LT₅₀of the suspension (10⁷ conidia/mL) for the 3rd instar larvae of S. frugiperda was 3.88 days. [Conclusion] The optimal medium for solid-state fermentation of SZCY was husked rice. With this medium and the optimal fermentation parameters, the conidium yield was higher and the yielded conidia show strong virulence to S. frugiperda. Therefore, SZCY should be further developed for biocontrol.

Abstract:[Background] Shajiang black soil is characterized by heavy texture, poor structure, and low fertility. The long-term straw returning in the area with Shajiang black soil leads to stunted growing of crops and slow straw decomposition. [Objective] To accelerate straw decomposition and increase crop yield, we screened a strain producing both carboxymethyl cellulase (CMCase) and indoleacetic acid (IAA) from Shajiang black soil. [Methods] The strain was identified based on physiological and biochemical properties and 16S rRNA gene sequence analysis. Shake flask of straw decomposition and maize pot experiments were carried out to verify the straw-decomposing, growth-promoting, and soil-improving effects of the strain. Single factor tests were then carried out to optimize the conditions for strain growth and IAA production. Green fluorescent protein (GFP) gene was introduced into the strain cells by electroporation and verified by PCR combined with agarose gel electrophoresis. The colonization rate was determined by fluorescence quantitative experiment. [Results] The straw-decomposing and maize growth-promoting strain was screened out and named as MC29, which belonged to Cellulosimicrobium cellulans. It presented the CMCase activity of 13.32 U/mL and the IAA production of 8.63 mg/L. Compared with the control, the application of MC29 increased the straw decomposition rate by 24.8% and the soil and plant analyzer development (SPAD) value, total plant weight, root surface area, and root length of maize by 7.6%, 21.3%, 30.9%, and 18.3%, respectively. Furthermore, the strain increased the soil available nitrogen, available phosphorus, and available potassium by 68.1%, 5.8%, and 6.0%, respectively. The optimum growth conditions of strain MC29 were pH 7.0, liquid-loading volume of 25/250 mL, maltose as carbon source, and yeast powder as nitrogen source, while the optimum conditions for IAA production were pH 7.0, liquid-loading volume 50/250 mL, fructose as carbon source, and potassium nitrate as nitrogen source. The strain MC29-GFP was successfully constructed, which showed the colonization amount of 2.8×10⁵ to 9.5×10⁵ copies/g 15 days after inoculation in the Shajiang black soil, demonstrating good colonization ability. [Conclusion] C. cellulans MC29 has the ability of decomposing straw and promoting maize growth, which plays a role in the development of multifunctional straw-decomposing agent and microbial fertilizer and the yield improvement of maize. The good and stable colonization ability lays a foundation for the practical application of strain MC29 in Shajiang black soil.

Abstract:[Background] Hyperuricemia is a chronic metabolic disease caused by the disorder of purine metabolism and lactic acid bacteria can degrade purines. [Objective] To screen lactic acid bacteria that efficiently degrade purine nucleoside and analyze the probiotic properties. [Methods] High performance liquid chromatography was used to determine the strain with the strongest ability to degrade inosine and guanosine. What’s more, probiotic properties of the target strain were studied by drug sensitivity test, in vitro tolerance tests, and cell adhesion test. [Results] Lactobacillus fermentum SR2-6 was screened out, which had the highest degradation rates of inosine and guanosine (99.26% and 98.85%, respectively). This strain showed no resistance to five common antibiotics such as penicillin and chloramphenicol. The survival rate of the strain was 76.51% after treatment under pH 2.0 for 4 h. The count of the viable bacteria was up to 6.85 lg (CFU/mL) after 4 h treatment in artificial satiety intestinal juice. The number bacteria adhered to Caco-2 cells was (52.29±15.14) CFU/cell. [Conclusion] SR2-6 can efficiently degrade inosine and guanosine, with excellent probiotic properties. It is a potential superior strain for the prevention and adjuvant treatment of hyperuricemia and can be applied into the development of related functional products.

Abstract:[Background] The eastern foot of Helan Mountain in Ningxia was once regarded as the “golden zone” for wine grape growth and thus boasts high-quality wine. Wine produced in this area got the tile of geographical indication product and therefore this area was included in the protection catalogue for the product. [Objective] To screen excellent native yeast strains in Ningxia, compare and analyze the influence of each Saccharomyces cerevisiae strain on the aroma quality of Cabernet Sauvignon, and select strains with great influence on wine flavor according to sensory evaluation. [Methods] The 26S rDNA sequencing was performed on the 11 selected strains which featured rapid fermentation at the early stage and strong tolerance to high alcohol concentration, SO₂, glucose, and low acid environment for identification. The aroma compounds of Cabernet Sauvignon fermented by different strains were determined by head space-solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). [Results] Eleven yeast strains which were tolerant to 15% alcohol, 500 g/L glucose, 350 mg/L SO₂, and pH 3.0 were screened out, among which 10 (H5, G9, G3, X8, G14, L10, H3, X11, Z17, and Z24) were identified as S. cerevisiae and one (L1) was Pichia fermentans. Esters were the main aroma compounds of Cabernet Sauvignon, followed by alcohols. Among them, ethyl acetate, isoamyl acetate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, 1-octene-3-alcohol and β-damascone had high odor activity values and contributed the most to the aroma of Cabernet Sauvignon, endowing the wine with pleasant apple aroma, banana aroma, mushroom aroma, anise aroma, and sweetness. Cluster analysis of aroma components of Cabernet Sauvignon samples fermented with different S. cerevisiae stains revealed that the wine samples fermented with G14 and H3 were the closest to the wine fermented with the commercial yeast XR and the three showed consistent influence on the characteristic aromas of Cabernet Sauvignon. [Conclusion] S. cerevisiae G14 and H3 have huge potential for brewing, particularly for wine fermentation, which can help improve the quality of wine in Ningxia.

Abstract:[Background] Due to the abuse of antibiotics, bacterial drug resistance has become a severe problem. Therefore, it is urgent to find useful strategies to solve the current situation of drug-resistant bacterial infections. In clinical, the combination of Chinese medicine and antibiotics is significantly effective in preventing drug-resistant bacterial infections. [Objective] To study the synergistic effect of carvacrol combined with ceftriaxone on drug-resistant Salmonella (SJ2) and the mechanism. [Methods] The minimum antibacterial concentration (minimal inhibitory concentration, MIC) of carvacrol and ceftriaxone on SJ2 was determined by broth microdilution method. The activity of carvacrol combined with ceftriaxone against SJ2 was determined by checkerboard method and growth curve. The effects of carvacrol combined with ceftriaxone on SJ2 cell wall and membrane were studied by membrane potential detection, extracellular alkaline phosphatase (alkaline phosphatase, AKP) content determination, antibiotic accumulation analysis in bacteria, bacterial viability determination, and scanning electron microscopy. [Results] The MIC of carvacrol and ceftriaxone against SJ2 was 256 μg/mL and 2 048 μg/mL, respectively. The carvacrol and ceftriaxone had the synergistic effect on SJ2, and their fractional inhibitory concentration index (fractional inhibitory concentration index, FICI) was 0.375. Carvacrol combined with ceftriaxone depolarized the SJ2 cell membranes, and significantly increased the amount of extracellular AKP (P<0.05), the intracellular antibiotic accumulation (P<0.01), and the number of bacteria that disrupted cell membrane integrity and caused serious damage of structure. [Conclusion] Carvacrol combined with ceftriaxone has the synergistic effect against SJ2, and the synergistic mechanism can be realized by damaging the bacterial cell wall and cell membrane.

Abstract:[Background] Bacillus is attractive for use as probiotic supplement in animal feed. With potent antimicrobial activity, Bacillus siamensis has drawn wide attention. [Objective] whole-genome sequencing and bioinformatics analysis were applied to explore the probiotic characteristics of the chicken-derived B. siamensis CML548 and clarify the antibacterial and potential probiotic mechanisms of this strain. [Methods] The antimicrobial activity, enzyme production, and tolerance to acid and bile salt were tested with the Oxford cup and spread plate method, respectively. The whole genome was sequenced by Illumina HiSeq 2500, followed by functional annotation and bioinformatic analysis of the genome. [Results] In vitro experiment suggested that this strain had probiotic features: inhibiting the growth of pathogenic Escherichia coli, Salmonella Typhimurium, and Clostridium perfringens, highly tolerating acid and bile salt, and producing protease, amylase, and cellulase. The genome of CML548 was 4 061 741 bp, with 3 961 coding genes and GC content of 46.07%. A total of 1 693, 2 704, 3 413, 186, 67, 1, and 5 genes were respectively annotated to GO, KEGG, COG, CAZy, DBAASP, CARD, and VFDB. antiSMASH predicted multiple gene clusters involved in the synthesis of secondary metabolites. In addition, CML548 contained an antibacterial protein-encoding gene tasA. The genome information was submitted to NCBI and the GenBank accession number is PRJNA836999. [Conclusion] CML548 is a candidate probiotic, which has the potential to be used as a feed additive.

Abstract:[Background] Bacillus subtilis YN145 is a bacterial strain isolated from healthy rice plants in Taojiang County of Hunan Province. Studies have demonstrated that YN145 has significant antagonistic effect against Magnaporthe oryzae and great potential in biocontrol. [Objective] To further study the biocontrol mechanism and screen out the gene clusters for secondary metabolite synthesis of this strain. [Methods] The strain YN145, whose extracellular substances had the best inhibitory effect on the melanin synthesis of M. oryzae, was selected from four biocontrol bacterial strains. The absorbance values of the extracellular and intramycelial melanin liquids of M. oryzae were measured by a UV-visible spectrophotometer at a wavelength of 400 nm. The antifungal activity of YN145 was determined by mycelial growth inhibition assay and conidial germination inhibition assay. PacBio Sequel IIe and Illumina Hiseq platforms were employed to sequence the whole genome of YN145, and the sequencing data were assembled and annotated for prediction of gene functions and analysis of the gene clusters for secondary metabolite synthesis. [Results] The extracellular antimicrobial substances of YN1145 effectively inhibited the melanin synthesis, conidial germination, and mycelial growth of M. oryzae. The full-length genome of YN1145 was 4 167 871 bp, with the GC content of 43.86% and coding sequence (CDS) number of 4 294. A total of 85 tRNAs, 30 rRNAs, and 92 sRNAs were identified in the genome. Meanwhile, five known gene clusters for secondary metabolite synthesis were predicted, which mainly encoded bacillaene, bacillibactin, fengycin, subtilosin-A, and baclysin. [Conclusion] This study analyzed the intrinsic reasons for the good antimicrobial effect of YN145 at the genome level and obtained rich basic data. It provides a reference for further in-depth research on the secondary metabolite synthetic pathway of B. subtilis and has great significance for the subsequent research of YN145.

Abstract:[Background] V-myb avian myeloblastosis viral oncogene homolog (MYB) transcription factors, which are ubiquitous in fungi, are vital in stress response and pathogenicity of the microbes. Cladosporium sp., parasitizing rust fungi, is a potential candidate for biocontrol. However, no report of its MYB transcription factors is available. The identification and expression analysis of its MYB transcription factor family are of great significance for understanding role of Cladosporium sp. in mycoparasitism. [Objective] To clarify the number of MYB transcription factors in Cladosporium cladosporioides SYC63 strain and the roles in the mycoparasitism. [Methods] We predicated fundamental characteristics of the MYB transcription factors with bioinformatics methods and analyzed the expression of them in the presence of aecidiospores. [Results] C. cladosporioides SYC63 harbors 22 MYB transcription factor genes and all the MYB transcription factors contain the SANT domain with molecular weight of 28.26–239.05 kDa and pI of 4.57–10.15. They are all hydrophilic proteins and mostly located in the nucleus. These genes can be classified to 1R-MYB and 2R-MYBs, which contain promoter binding sites for the response to pathogens. After rust spore induction, most SycMYBs were down-regulated, and only six genes were up-regulated. Eight genes with high expression or great fold change were selected for RT-qPCR, and the results suggested different change trends of expression after the induction for different time. Among the eight genes, SycMYB6 kept at a high level during the infestation. [Conclusion] MYB transcription factors play a role in the response to infestation and stress resistance of strain SYC63 during the mycoparasitism. The result is expected to lay a theoretical basis for further exploring the role of MYB transcription factor family in fungi and the mycoparasitim mechanism of Cladosporium sp..

Abstract:[Background] There is increasing evidence that intestinal imbalance is associated with immune-mediated disease. However, the mechanistic link between intestinal flora and immune-mediated kidney disease remains unclear. [Objective] To compare the intestinal flora by using high throughput 16S ribosomal RNA (rRNA) gene sequencing between patients with immunoglobulin A nephropathy (IgAN) and membranous nephropathy (MN) and healthy people. [Methods] Fresh fecal samples from patients with IgAN and MN who underwent renal biopsy in the Department of Nephrology of Gansu Provincial Hospital from September 2020 to December 2021 were retrospectively selected and divided into an IgAN group and a MN group, and the fecal samples from healthy people in the physical examination center were collected as a healthy control group, with 10 cases in each group. The 16S rRNA gene V3−V4 region of all bacteria in fecal samples was sequenced by high-throughput sequencing technology, and then biodiversity analysis was performed, including operational taxonomic units (OTU) analysis, species classification analysis, alpha diversity analysis, beta diversity analysis, etc., to compare the intestinal flora differences among the three groups. [Results] As compared with the healthy control group, Proteobacteria and Actinobacteria at phylum level in the IgAN group were significantly increased (18% vs. 4% and 18.3% vs. 5%, respectively). The abundance of Escherichia-Shigella and Bifidobacterium at genus level was significantly higher in the IgAN group (14.1% vs. 2.1% and 17.5% vs. 4.7%, respectively), while the abundance of Faecalibacterium (11% vs. 20.5%), Bacteroides (8.0% vs. 21%), and Megomonas (1.8% vs. 8.0%) was significantly lower. The abundance of Proteobacteria at phylum level increased in the MN group as compared with the healthy control group (20% vs. 4%). At genus level, the abundance of Escherich-Shigella increased in the MN group (13.8% vs 2.1%), the abundance of Bifidobacteria (3.2% vs. 4.7%), Faecalibacterium (18% vs. 20.5%), Bacteroides (14.3% vs. 21%), and Megomonas (1% vs. 8%) decreased. Alpha diversity analysis showed that the richness index of the IgAN and MN groups was lower than that of the healthy control group, and the diversity index was higher than that of the healthy control group. Principal coordinates analysis (PCoA) showed statistically significant differences in the composition of intestinal flora between the IgAN group and the healthy control group (ANOISM, R=0.19, P=0.013). There were differences in the composition of intestinal flora between the MN group and the healthy control group, but the results were not statistically significant (ANOISM, R=0.08, P=0.08). Linear discriminant analysis (LDA) for differential contribution revealed that 14 species had significant differences among the three groups. [Conclusion] The intestinal microbiome characteristics of patients with IgAN and MN are different from those of healthy people.

Abstract:The rhizosphere microbiome is one of the key determinants of crop health and an important factor regulating crop interactions with biotic and abiotic environments. Plant growth-promoting rhizobacteria (PGPR) interact with crops and soil in complex ways through chemical communication to promote crop growth. This paper reviewed the growth-promoting mechanism of PGPR on crops, the interaction between PGPR and crops and its application in agricultural practice, and the development trend of the application of PGPR in agricultural practice was also prospected, aiming to provide new ideas and theoretical support for the application and research of PGPR in future.

Abstract:In recent years, the global outbreak of COVID-19 has aroused public attention to the potential risks of bioaerosols and the studies about the potential health hazards of bioaerosols from anthropogenic sources have been increasing. We introduced the research status of four main anthropogenic bioaerosols in recent years, compared the distribution and composition characteristics of bioaerosols from different anthropogenic sources, and analyzed the main factors affecting the characteristics and potential risks of bioaerosols. The average concentration of bioaerosol is high in animal farms, moderate in wastewater treatment plants and landfills, and low in hospitals. The microbial composition of bioaerosols at different sites is closely associated with the bioaerosol source and affected by the environmental conditions. Furthermore, this work prospected the main research directions of anthropogenic bioaerosols in the future, aiming to lay a foundation for the establishment of bioaerosol control standards and the development of control technology.

Abstract:Codonopsis pilosula is a commonly used herbal medicine with edible value in people’s daily life and has tonifying effect. Polysaccharide as one of the main active components of C. pilosula has a variety of biological activities. In recent years, scholars have achieved remarkable progress in the study of C. pilosula polysaccharide in the treatment of intestinal diseases. The studies have demonstrated that intestinal flora may be a target for C. pilosula polysaccharide in the treatment of intestinal diseases. This paper summarizes the role of C. pilosula polysaccharide in the regulation of intestinal microecology and intestinal diseases, aiming to provide a theoretical and experimental basis for the development of C. pilosula polysaccharide as a prebiotic preparation and the treatment of intestinal diseases.

Abstract:Cognitive decline, a major characteristic of brain aging in the elderly, is associated with the increasing inflammatory reaction, decreasing antioxidant capacity, the impairment of blood-brain barrier, and the structural change of hippocampus. Increasing studies have demonstrated that the changes of gut microbiota in the aging people are an important factor of cognitive impairment, which have gradually become a research hotspot. Gut microbiota can regulate the cognitive function of the elderly through gut-brain axis. They can affect the memory, emotion, and other cognitive domains of the elderly through the neurotransmitters, vagus nerve, nerve endocrine, and immunomodulation. Moreover, they can influence the cognitive function by regulating the beta-amyloid deposition, lipopolysaccharide levels, and the development and maturation of microglia. We reviewed the recent advances in research on gut microbiota and cognitive functions of the elderly, aiming to provide new ideas for the prevention and rehabilitation of cognitive impairment-related diseases in the elderly.

Abstract:There is no way to reverse spinal cord injury. In the case of spinal cord injury, patients always suffer from gastrointestinal dysfunction which impacts the quality of life. It has been reported that gut microbiota disorder after spinal cord injury is connected to the gastrointestinal dysfunction. Thus, this paper mainly explored the role of gut microbiota in vagus nerve system, hypothalamic-pituitary-adrenal axis and gut microbiota metabolites three pathways, and the relationship with gut inflammatory through gut microbiota changes after spinal cord injury.

Abstract:Gut microbes, known as the body’s “second gene pool”, play a role in the treatment of osteoporosis. They affect the connection between intestinal tract and bone metabolism through intestinal epithelial barrier, immune system, endocrine system, and intestinal flora metabolites in the gut-bone axis. Novel gut microbiota-targeted therapies such as probiotics, prebiotics, and dietary supplements have been shown to be effective in preventing bone loss. However, their long-term efficacy and safety still need to be further enhanced. Therefore, this paper discusses the main role of the microbe-gut-bone axis in osteoporosis, which is expected to provide new ideas for the treatment of this disease.

Abstract:The high incidence of osteoporosis in the aging population reduces the quality of life. There is growing evidence that the gut microbiota is closely linked to bone metabolism. Gut microbiota disorder will lead to pathophysiological responses in the host, which can cause osteoporosis. The research on the interactions between gut microbiota and osteoporosis may contribute to the management of osteoporosis-related conditions. This paper reviews the advances in the interactions between gut microbiota and osteoporosis and the relevant therapies.

Abstract:The balance of oral microbiota is a key factor in maintaining oral health. Prebiotics are a kind of organic substances that selectively promote the metabolism of beneficial microorganisms. They mainly exert their functions by adjusting the oral microbial growth and metabolism, inhibiting the formation of dental plaque biofilm, regulating the host immune response and oxidative stress response, and participating in the nitrate-nitrite-nitric oxide pathway. Studies have demonstrated that prebiotics play a positive role in the prevention and treatment of common oral diseases, such as dental caries, periodontal diseases, and oral mucosal disease, and are expected to become a potential way to prevent and treat oral diseases. This article reviews the recent research progress in prebiotics, their effects on oral health, and the mechanisms of prebiotics in regulating oral microecology.

Abstract:Food Microbiology, with a strong theoretical and abstract nature, is a practical main course for undergraduates majoring in Food. In the context of new engineering education, the teaching of Food Microbiology has some problems, such as the poor ideological and political education, weak innovation ability of students, and unsound collaborative cultivation system. Insisting on the student-centered teaching concept and the cultivation of students’ abilities in scientific research and engineering practice, we created the teaching reform idea combining online and offline teaching. Through the integration of ideological and political education with course education, of scientific research with classroom learning, and of regional industry and professional teaching, the advantages of disciplines and industries were transformed into innovative teaching resources. In this way, the goal of being high-level, innovative, and challenging was achieved. The teaching reform of the course succeeded in realizing the resonance of talent training and ideological and political education and empowering the cultivation of innovative talents majoring in food.

Abstract:With the state’s new requirements for the cultivation program of talents in higher vocational education, as well as the rapid development of information technology and the diversification of student sources, the outdated practical teaching system can no longer meet the needs. Based on the current problems in the teaching of Microbiological Testing Technology, the teaching team of this course takes the workplace as the leader, closely integrates the needs of talents in enterprises, introduces relative cases in daily life to stimulate students’ interest in learning, integrates the experimental projects of related courses to establish an experimental system gradually. Meanwhile, the proportion of process assessment of practical courses is increased so that students pay attention to each practical teaching. The above teaching reforms not only have significantly improved the quality of teaching, but also inspired students’ thinking, stimulated their interest, cultivated students' scientific research literacy and improved their comprehensive literacy so that the students’ graduation and employment are connected seamlessly.

Abstract:Microbiology Experiment is a compulsory core course for bioengineering majors. In combination with the school’s “four in one” education concept, the course objectives in line with experimental teaching were established based on Bloom’s taxonomy of educational objectives, and the three-dimensional course objectives of knowledge, ability and ideology and politics were innovatively designed. Under the engineering certification of higher education, the Microbiology Experiment course has been continuously improved for three consecutive sessions; the achievement degree of graduation index has been analyzed and studied; the improvement measures have been proposed; which was worthy of experimental teaching research and promotion.

Abstract:微生物资源是国家战略性生物资源，是支撑微生物学科发展与技术创新的重要基础。可直接开发为食品原料或用以酿造生产，也可作为服务农牧业生产菌剂产品或用于生产医疗药品和清洁能源，已经在工业、农业、食品、酿造、医药、能源及环境等领域得到广泛应用。近年来，随着生物技术及分子生物学等研究的发展，在微生物资源的分离、评价、保藏等方面都取得了较大进展。《微生物学通报》组织了本期“微生物资源：发掘、利用、展望与挑战”专栏，旨在展示微生物资源学领域的最新进展，加强微生物种质资源的发掘、利用，助力微生物资源学科和科技创新战略发展。

Abstract:[Background] Ginger wilt caused by Ralstonia solanacearum (R.S) is a bottleneck in the development of the ginger industry. Arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) are two kinds of important symbiotic microorganisms. [Objective] To explore the mechanism of AMF and DSE against ginger wilt. The previous study found that AMF and DSE could improve the resistance of ginger wilt, however, the synergic functioning mechanism was unclear, which limited the application of the two kinds of fungi to control the disease. [Methods] The pot experiments were carried out at room temperature with ginger-cultured seedlings as the material. The control (CK) treatment inoculated with AMF and DSE and without AMF and DSE were set up. After 4 weeks of growth under the above treatment, the plants were eluted with pathogen solution. One week after pathogen inoculation, the effects of AMF and DSE on the ginger growth and physiological and biochemical indexes infected with the pathogen were studied by determining the mycorrhizal infection rate, incidence, chlorophyll content, photosynthetic index, phosphorus (P) content, defensive enzyme activity, and malondialdehyde (MDA) content. [Results] AMF and DSE reduced the incidence of ginger wilt in ginger by 45.27% and 52.04%, respectively (P<0.05). AMF+DSE had a better effect on the prevention and control of this disease, and the incidence was reduced by 60.87% as compared with the control (P<0.05). The preventive effects of AMF, DSE, and AMF+DSE were 62.54%, 59.02%, and 68.50%, respectively. The activity of plant defensive enzymes indicated that AMF significantly increased the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and polyphenol oxidase (PPO) by 10.87%, 1.15%, 13.26%, and 0.14%, respectively. DSE significantly increased the activities of SOD, POD, CAT, and PPO by 9.85%, 17.47%, 3.64%, and 0.67%, respectively. AMF+DSE significantly increased the activities of SOD, POD, CAT, and PPO by 15.76%, 18.19%, 18.11%, and 14.93%, respectively (P<0.05). AMF, DSE, and AMF+DSE significantly decreased the content of MDA by 3.38%, 9.31%, and 25.79%, respectively (P<0.05). [Conclusion] AMF and DSE have preventive effects on ginger wilt, which improve the disease resistance of ginger seedlings and promotes their growth, and the combination of AMF and DSE manifests the optimal effect.

Abstract:[Background] The current studies about the fermentation of Chinese sauerkraut mainly focus on Lactobacillus plantarum, while there are few reports on L. brevis in Chinese sauerkraut. [Objective] To explore the fermentation performance of L. brevis and develop the starter of Chinese sauerkraut fermentation, we designed two strain combinations (two strains of L. brevis and one strain of L. plantarum) for fermentation to explore the effect of L. brevis on the quality of Chinese sauerkraut. [Methods] The growth, acid production capacity, acid resistance, and nitrite degradation capacity of single strains of L. brevis and L. plantarum were measured. During days 1-7 of the fermentation with the two strain combinations, the acidity, viable cell count, nitrite content, and texture changes of Chinese sauerkraut were measured. [Results] L. brevis Lb-5-3 had slower growth and acid production rate, weaker acid tolerance, and stronger nitrite degradation ability than L. brevis Lb-9-2. After the two strains were respectively combined with L. plantarum Lp-9-1, their acid production significantly increased and the pH value was the lowest (about 3.10) on day 3. The addition of Lp-9-1 delayed the growth of Lactobacillus in Chinese sauerkraut and the viable cell count peaked on day 5. The nitrite content of the samples inoculated with the combined strains varied gently from day 1 to day 7 and showed no significant difference between the two combinations in the first 5 days. The inoculation of Lactobacillus decreased the hardness and elasticity of Chinese sauerkraut, and the hardness was the highest on day 3 of fermentation with the combination of Lb-5-3/Lp-9-1. The sensory score of the Chinese sauerkraut fermented with Lb-5-3/Lp-9-1 was the highest on day 3 of fermentation. [Conclusion] Therefore, the combination of L. brevis and L. plantarum could produce Chinese sauerkraut with low nitrite content and good comprehensive properties within 3 days. L. brevis in the strain combination did not affect the acid production or nitrite degradation, while it affected the hardness and sensory properties of Chinese sauerkraut. This study is of great significance to the performance evaluation of new Lactobacillus strains and the development of starter for the production of Chinese sauerkraut.

Abstract:[Background] Bacterial wilt is a serious disease attacking Eucalyptus. Arbuscular mycorrhizal fungi (AMF) affect the resistance of Eucalyptus to bacterial wilt, the mechanism of which remains unclear. [Objective] To explore the responding mechanism of AMF of Eucalyptus grandis during the infection course of Ralstonia solanacearum. [Methods] In this study, the non-mycorrhizal root tissue and the Rhizophagus irregularis-colonized root tissue of E. grandis were sampled at the time points of 0, 24, 48, and 96 hour post inoculation (hpi) of R. solanacearum. The genes involved in the response of R. irregularis in E. grandis roots to R. solanacearum infection were screened and identified by transcriptome sequencing. [Results] Compared with the non-mycorrhizal root tissue, R. irregularis showed 3 382-5 989 differentially expressed genes at different time points of E. grandis infection by R. solanacearum. The number of specifically differentially expressed genes of R. irregularis in response to R. solanacearum infection gradually increased over the infection time. R. irregularis significantly enriched the genes involved in AMF symbiont growth, sporulation, and apoptosis signaling pathways and siderophores at 24 hpi. At 48 hpi, R. irregularis mainly improved the transmembrane transport and promoted the absorption and exchange of nutrients such as potassium and nitrogen. At 96 hpi, R. irregularis mainly regulated the redox reaction and the synthesis of antibacterial substances such as flavonoids. [Conclusion] The AMF of E. grandis mainly regulate the plant growth, enhance the niche and nutrient (such as nitrogen, potassium, and iron) competition, secrete antimicrobial substances, and activate the defense response to R. solanacearum infection. The identified genes provide resources and references for further deciphering the mechanism of AMF-Eucalyptus-R. solanacearum interaction.

Abstract:Microorganisms are ubiquitous on the earth, with high diversity and a variety of functions. They play an irreplaceable role in human health, ecological stability, and species evolution. Despite the endeavor in the isolation, research, and utilization of microorganisms since the 17th century, most microorganisms cannot be obtained by the pure culture method, which has seriously hindered the research on microbial life activities and the development of microbial resources. The acquisition of the “dark matter” has always been a serious challenge. However, it is also an opportunity to break this shackle and obtain more microbial resources. This review introduces the influencing factors that restrict the isolation and incubation of microorganisms in the environments, describes the new culture techniques such as optimization of traditional culture strategy, co-occurrence network-based culture, membrane diffusion-based culture, microfluidics, and cell sorting, and puts forward the strategy of combining multiple techniques, with a view to providing reference for the development and utilization of microbial resources.

Abstract:Triketone herbicides with high efficiency, broad spectrum, and high selectivity can effectively control a variety of broadleaf weeds and gramineous weeds in maize fields. The residues of the herbicides in soil and water are easy to cause surface and ground water pollution. Studies have indicated that microbial degradation is expected to be an effective measure to solve herbicide residues. In this paper, we analyzed the ecological effects of two triketone herbicides, summarized the reported microbial resources for residue degradation, and briefed the research progress in the degradation genes/enzymes and possible degradation ways, aiming to provide information support for further research on the biodegradation of triketone herbicides.

Abstract:[Background] Xinjiang of China, with its vast land and diverse climate types, which harbors high diversity of endemic microbial resources. [Objective] Based on bibliometrics, to explore the status and trend of newly discovered microbial resources in the special environments of Xinjiang. [Methods] We searched against IJSEM and other mainstream journals that publish newly discovered species with “Xinjiang” as the keyword and the time interval of 2000 to 2021. A total of 321 articles involving 348 strains of endemic species newly discovered in Xinjiang were screened out and used for bibliometric analysis. VOS viewer was used for the visual analysis of the keywords, publishing dates, authors and affiliations. [Results] The number of literatures published on new species showed an overall trend of fluctuation and increase, and the major publishing affiliations were Yunnan University and Tarim University. The high-frequency keyword was soil microorganisms, the taxonomic status, isolation methods, and potential application values of all the newly discovered species were summarized. [Conclusion] Based on bibliometrics, the overview and related research trend of new microbial resources in Xinjiang were analyzed. We hope that this paper will provide a reference for the systematic mining of microbial germplasm resources endemic to Xinjiang in the future.