Abstract:[Background] Maize sheath blight has grew into the main disease that restricted the increase in maize production in China. Validamycin A and biocontrol microbe Trichoderma sp. both have resistance to sheath blight but each of which provides benefits and drawbacks. [Objective] To study the synergy of Validamycin A and Trichoderma for the control of sheath blight of maize. [Methods] We determined the effect of Validamycin A on cell wall degradation enzymes and related enzyme in defense reaction of Trichoderma asperellum GDSF1009. We used tobacco leaves to validate reactive oxygen and its allergic reactions. We also used the transcriptome and gas chromatography-time of flight-mass spectrometry to analyze Validamycin A’s effect on the expression difference of genes, the growth and the metabolism of GDSF1009 and carried out the experiment on the synergistic inhibition of leaf and plate. [Results] Validamycin A had no effect on the activities of chitinase, cellulase and xylanase of GDSF1009 and did not get into the cell. At the level of transcriptome, compared with the controls, the proportions of different genes in Trichoderma asperellum were 8.932% and 6.779% respectively after 24 h and 48 h treated by Validamycin A. Validamycin A had no significant influence on carbohydrate and lipid and only had some influences on genes related to amino acid metabolism. These genes would not change amino acid metabolism much. Furthermore, the combination of the Validamycin A and Trichoderma asperellum can significantly improve the effect of prevention of maize sheath blight. [Conclusion] Validamycin A is safe for the primary metabolic system of Trichoderma asperellum. The resistance of the synergy is significantly higher than that of the single factor.

Abstract:[Background] Approximately 2.9×1029 cells reside in marine sediments, roughly equal to the estimates of cell abundance in seawater. Due to the lack of cultivated representative species of these microbes in laboratories, their physiology and metabolic functions remain largely unknown. The members of Bathyarchaeota are typical sedimentary microorganisms and widely distributed in global marine sediments. [Objective] For further understanding of their metabolic potential and ecological roles that remain largely elusive. [Methods] Samples from Guaymas Basin hydrothermal sediment were analyzed by metagenomic technology, and a near-complete genome belonging to Bathyarchaeota B242 was obtained. [Results] Through comprehensive genomic analysis, Bathyarchaeota B242 was found having heterotrophic mode of life style mainly through protein fermentation, carbohydrate utilization as well as possess autotrophic acetogenic pathway that helps survive under energy deficient environments. [Conclusion] The heterotrophic and autotrophic metabolic mode together contributed to the adaptation in energy deficient marine sediments for Bathyarchaeota.

Abstract:[Background] Lactic acid bacteria are important in liquor fermentation, and the diversity and succession of lactic acid bacteria have important influence on liquor quality. However, the structure and succession of lactic acid bacteria communities are not clear during sesame-flavor liquor fermentation. [Objective] We studied the diversity and succession of lactic acid bacteria communities during sesame-flavor liquor fermentation for better process control and product quality. [Methods] High-throughput sequencing was used to analyze lactic acid bacteria communities during sesame-flavor liquor fermentation. Biomass of lactic acid bacteria was quantified by real-time qPCR. [Results] Lactic acid bacteria in sesame-flavor liquor fermentation included Weissella, Pediococcus, Lactobacillus, Leuconostoc, and Lactococcus, classified to 43 species. Ten species of lactic acid bacteria were observed higher than 0.5%, including Weissella paramesenteroides, Weissella cibaria, Weissella confuse, Pediococcus pentosaceus, Leuconostoc pseudomesenteroides, Lactobacillus fermentum, Lactobacillus plantarum, Lactobacillus paracasei, Lactobacillus acetotolerans and Lactobacillus sp.. In heap-fermentation stage, Weissella was more than half of the total bacteria, followed by Pediococcus and Lactobacillus. Leuconostoc and Lactococcus were present in low numbers. In pit-fermentation stage, Lactobacillus became the predominant bacteria, and the relative abundance of Lactobacillus sp. was up to 80% in the mid and later stage of pit-fermentation. During heap-fermentation and the early stage of pit-fermentation, the biomass of lactic acid bacteria changed little. After 5 days of pit-fermentation, the biomass of lactic acid bacteria increased fast, and reached the maximum at 30 days. [Conclusion] The knowledge of diversity and succession of lactic acid bacteria during sesame-flavor liquor fermentation will help understand the roles of lactic acid bacteria in liquor production with better process control and product quality.

Abstract:[Background] Filamentous fungi are important production strains in fermentation industry, and their morphology is related with the production of target products. Rhizopus chinensis CCTCC M201021 is an important filamentous fungus isolated from Daqu for Chinese liquor, produces some important industrial enzymes, such as lipases. [Objective] Rhizopus chinensis CCTCC M201021 can form two typical mycelia morphology, the aggregated and dispersed, in submerged culture with different fermentation performance. The objective of this work was to study the intrinsic difference associated with different mycelia morphology based on transcriptome profiles of R. chinensis. [Methods] Based on high throughput RNA sequencing, gene transcriptions of high expression and significantly differential expression from R. chinensis mycelia with different morphology were compared. [Results] RNA sequencing released the significant difference in the transcriptomes of mycelia with different morphology. In the 20 genes featuring the highest RPKM values in the transcriptome of the aggregated or dispersed mycelia, most genes with the highest RPKM value were ribosomal proteins genes in the aggregated mycelia. Chitinase genes and signal transduction genes were found in the dispersed R. chinensis in addition to some ribosomal proteins genes. Analysis of 20 most up-regulated genes in the transcriptome of the aggregated or dispersed mycelia indicated that differential genes associated with cellular process and signaling were up-regulated in dispersed mycelia, besides significantly differential genes related to metabolism. The value of RPKM suggested that most of unique transcribed genes in both mycelia were transcribed at a low level, whereas those in the aggregated mycelia were more various and with higher value of RPKM than the dispersed one. Moreover, the higher lipase activity of aggregated R. chinensis agreed with the higher transcription level in the cells. [Conclusion] Our findings indicate intrinsic mechanisms of mycelia morphology differentiation and their influence on metabolism.

Abstract:[Background] Zygosaccharomyces bailii is a dominant strain in Chinese Maotai-flavor liquor spontaneous fermentation. However, the effects of other functional strains on Z. bailii is unclear. [Objective] We studied the effects of three other main strains on Z. bailii by co-culture. [Methods] Z. bailii was separately cultured with Saccharomyces cerevisiae, Lactobacillus buchneri, or Bacillus licheniformis. Biomass, pH, ethanol and flavor compounds were determined during the fermentation. Based on the analysis of phenotypic differences, a comparative transcriptome analysis was used to reveal the fermentation mechanisms of Z. bailii in mixed culture with B. licheniformis. [Results] In mixed cultures, the growth and ethanol production of Z. bailii were inhibited by S. cerevisiae, whereas were not affected by L. buchneri or B. licheniformis. Meanwhile, flavor compounds production of Z. bailii was reduced by S. cerevisiae or L. buchneri, but was promoted by B. licheniformis and among them, alcohols, acids, esters and aldehydes increased by 41%, 36%, 44% and 73%, respectively, compared with those in the Z. bailii single culture. Transcriptome analysis of Z. bailii showed that genes related to the metabolism of carbohydrate and amino acids, were significantly up-regulated (≥2-fold, P<0.05) in mixed culture with B. licheniformis. Flavor compounds mainly derived from the metabolism of carbohydrates and amino acids. Therefore, those up-regulated genes might be beneficial for flavor compounds production of Z. bailii. [Conclusion] Z. bailii produced more favor compounds in the co-culture fermentation with B. licheniformis, including alcohols, acids, esters and aldehydes.

Abstract:[Background] Pepper Phytophthora blight, caused by Phytophthora capsici, is one of the most devastating diseases of pepper growing areas worldwide. Biological control has drawn more and more attention in recent years for its safety to environment, human and animal. [Objective] To screen and identify a marine bacterium strain SH-27 against phytophthora capsici and study its effects on disease control and growth promotion on pepper. [Methods] Antagonistic marine bacteria were isolated by serial dilution and dual culture. The effects of controlling disease and growth promotion on pepper seedlings were studied by using the fermentation broth of strain SH-27. Strain SH-27 was identified by morphological characteristics, physiological and biochemical tests and 16S rRNA and gyrA gene sequence analysis. [Results] A total of 142 bacterial isolates were obtained. Among them, 11 strains displayed the antagonistic activity to Phytophthora capsici. Especially strain SH-27 isolated from corals displayed high antagonistic activity and broad antimicrobial spectrum. Pot tests showed that the root length, plant height, stem diameter, fresh weight and dry weight of pepper plant treated with SH-27 fermentation broth were promoted significantly when compared to the control treatment. The control efficacy of strain SH-27 to pepper phytophthora blight were 70.81%, 66.55% and 48.20% when the pathogens were inoculated after 4, 6 and 9 days respectively. Based on characteristics in morphology, physiology, biochemistry, 16S rRNA and gyrA gene sequence analysis, strain SH-27 was identified as Bacillus amyloliquefaciens. [Conclusion] Due to its effects of disease control and growth promotion on pepper, strain SH-27 is possible to be further developed as an excellent strain for microbial fertilizer and fungicide.

Abstract:[Background] A special extracting raw material with low cost is extremely urgent, as the expense of extracting unsaturated fatty acids from fish and crops is growing high. The particularity of ocean environment results in a rich and unique microbial resource, which have been regarded as a new strategy for obtaining unsaturated fatty acids. [Objective] The aim was to isolate oil-producing fungi from Scagassum collected from Xuwen Port, Zhanjiang, Guangdong Province, and analyze its fatty acid composition by gas chromatography (GC). [Methods] The selective plating medium and method of Sudan Black B staining were used to screen high-yield oil-producing fungi. The target strain was identified by morphological and culture characteristics and analysis of ITS sequences. GC was used to determine the composition and content of the lipids which were extracted by chloroform-methanol. [Results] A total of 7 oil-producing fungal strains were screened, among which strain A17 was the high-yield oil-producing fungus with larger lipochondrion. The analysis of morphology and molecular identification of ITS sequence showed that the strain A17 was Fusarium incarnatum. The oil extracted from the strain A17 accounted for 24.75% of the cell dry weight, and unsaturated fatty acid accounted for 60.76% of the total oil content, which oleic acid and linoleic acid were 32.80% and 26.20 %, respectively. [Conclusion] This study may provide a theoretical base for the development of oil-producing strains in Scagassum.

Abstract:[Background] Only a small proportion of microbes can be cultured in laboratories, thereby hampering the discovery of novel β-glucosidases from microbes. Novel microbial β-glucosidases can be discovered using culture-independent metagenomic approach. [Objective] Discovery of new β-glucosidase from soil microbes by metagenomic technology. [Methods] Screening a metagenomic library on esculin-containing Luria-Bertani agar plates and the putative β-glucosidase gene derived from the active clone was heterologously expressed for characterization. [Results] We found a?β-glucosidase active clone by screening 620 000 clones in the library and an ORF (YNBG3) whose product is homologous with the third family of β-glucosidase was identified from the active clone. YNBG3 was heterologously expressed and characterized. Its optimum pH is 5.2, and optimal temperature is 53 °C. YNBG3 showed good tolerance to organic solvents including dimethyl sulphoxide, acetone and ethanol, and the activity of YNBG3 was enhanced in presence of EDTA and urea. [Conclusion] A new β-glucosidase, with thermostability and stability in the presence of organic solvents and urea, was discovery in this study.

Abstract:[Background] At present, the study on the endophytic actinobactreia from Entire meconopsis is relatively rare, the resource of endophytic actinobactreia from Entire meconopsis can be enriched with available culture and non-cultured methods. [Objective] To explore the diversity and community structure of endophytic actinobactreia from Entire meconopsis, a medicinal plant growing at high elevation, samples were collected from a special ecological environment in Aba, Sichuan Province. [Methods] Six different geographical positions were determined to sample and available culture method as well as PCR-DGGE technology was applied to investigate the diversity of endophytic actinobactreia from Entire meconopsis after a thorough surface disinfection. [Results] Based on culture method, the largest amount of isolates from different plant tissues was found in the root, followed in the leaf, stem and flower, respectively. The strains were grouped into 7 genotypes through 16S rDNA-RFLP Restriction fragment length polymorphism analysis, while representative strains were divided into 3 clusters in phylogenic analysis. Streptomyces was the dominant genus accounting for 50%, followed by Kitasatospora and Oerskovia and the greatest abundance of isolates was found in stem. The results of PCR-DGGE showed that the highest diversity index of endophytic actinobactreia was from root, stem and leaf that sampled in Galitai, Songpan and that from flower sampled in Anquxiang, Hongyuan. However, the largest diversity index in the same geographical position was from stem and flower. Additionally, the sequences in phylogenic analysis were classified into 8 genotypes including Rhodococcus, Corynebacterium, Nocardia, Micrococcus, Mycetocola, Microbacterium, Pseudonocardia and Streptomyces, among which Rhodococcus was predominant representing 70%. In general, it was a more effective way of combining available culture with uncultured methods to investigate the diversity of endophytic actinomycetes from Entire meconopsis. [Conclusion] The study revealed a rich diversity from different tissues in Entire meconopsis and laid foundation for further researches in active substances and medicine efficacy.

Abstract:[Background] Energy metabolism efficiency was an important component of measuring the utilization rate of the diet. Improving the digestion and metabolism efficiency of the energy contained in different nutrients by ruminants was helpful to improve the energy use efficiency of ruminants. [Objective] The objective of this study was to compare the structure and composition of ruminal microbiome of goats with different energy metabolism efficiency using Illumina MiSeq sequencing technology. [Methods] In total 19 goats were used as experimental animals, among them 5 goats with high energy metabolism efficiency were selected as HEU group and 5 goats with low energy metabolism efficiency as LEU group. Rumen fluid from each goat of HEU and LEU was collected and then total genomic DNA was extracted from the rumen fluids. High variable region of bacterial 16S rRNA genes was amplified by PCR using bacterial universal primers. Analyzing amplicon sequence data on the Illumina MiSeq sequencing platform and biological information analysis using QIIME software were done. [Results] Bacteroidetes (44.20%±9.39%), Firmicutes (16.40%±5.44%) and Proteobacteria (11.30%±7.42%) were the dominant bacteria in the rumen microorganisms of goats, among them Firmicutes was the dominant bacteria shared by the two groups. The relative abundance of Bacilli from LEU group (6.71%±2.47%) was significantly higher than that from HEU (P<0.05). The relative abundances of Lactobacillales of the two groups were the highest at the order level, and the relative abundance from LEU (4.98%±1.88%) was significantly higher than that from HEU (P<0.05). At the family level, the relative abundances of 7 families were significant differences in the two groups (P<0.05). The relative abundance of Bacteroidaceae was highest in the two groups, and Bacteroidaceae from group LEU (3.64%±1.32%) was significantly higher than that of group HEU (P<0.05). At the genus level, the relative abundances of 9 genus were significant differences (P<0.05). Only the relative abundance of Prevotella sp. from HEU (0.61%±0.36%) was higher than that in LEU (0.16%±0.07%), but the relative abundances of other 8 genus were significantly lower than LEU (P<0.05). The relative abundance of Ruminococcaceae sp. was the highest in HEU group (2.53%±0.62%) and LEU (4.19%±1.43%). [Conclusion] There are significant differences about structure and composition of rumen microorganisms among goats with different energy metabolism rate.

Abstract:[Background] Saline-alkali land area in China is big, wide distributed and diversified, which is mainly distributed in northeast, northwest, north and coastal areas in China. The research in recent years has shown that the bioremediation by inoculation of PGPR can improve resistance of plants to salt stress, increasing the saline-alkali land management. [Objective] To preliminarily discover the growth promoting effect and mechanism of Enterobacter sp. FYP1101 on wheat seedling under salt stress, and to provide the theoretical basis for the field application of the strain. [Methods] On medium of phytate-phosphorus, using spread and streak plating technique to isolate; on Ashby medium and inorganic-phosphorus medium, the bacteria of nitrogen-fixation and inorganic-phosphorus-solubilizing were screened preliminarily, then analyzed their abilities for nitrogen-fixation, phytate-phosphorus-solubilizing, inorganic-phosphorus-solubilizing, siderophore- producing, 1-aminocyclopropane-1-carboxylate (ACC)-deaminase-producing and indole acetic acid (IAA)-producing; 16S rRNA gene was applied to preliminarily and taxonomically classify the strain FYP1101; plotted wheat under salt stress and conducted 3 treatments (treatment FP, adding particle microbial fertilizer containing FYP1101; treatment NK, adding null particle carrier containing no bacterial inoculant; treatment CK, neither particle microbial fertilizer nor null particle carrier added), then compared the shifts of the growth traits and physiochemical properties of rhizosphere soil of wheat seedlings under salt stress between different treatments. [Results] A total of 96 rhizospheric strains were isolated; one isolate designated by FYP1101 has salt tolerance up to 8%, and showed strong abilities of nitrogen-fixation (nitrogenase activity of 2.59 nmol C2H4/(h?mg protein)), phytate-phosphorus-solubilizing (2.70 μg/mL), inorganic-phosphorus-solubilizing (4.29 μg/mL), siderophore-producing (D/d ratio of 2.88), ACC-deaminase-activity (7.32 μmol α-butanone/(h·mg protein)) and IAA-producing (24.93 mg/L); based on 16S rRNA gene sequence, strain FYP1101 was classified into the genus of Enterobacter; Compared with NK and CK, the wheat inoculated by FP under salt stress showed chlorophyll content and biomass of overground and underground increased markedly (with increments of 19%?54%) and root length also increased markedly (with increments of 46%); the concentration of rhizospheric organic matter and available nitrogen were improved by about 52%?98%, whereas pH slightly decreased (0.12 and 0.17 units) and salinity increased about 40%. [Conclusion] Enterobacter sp. FYP1101 has many kinds of plant growth promoting traits. The strain can significantly affect the root establishment of wheat seedling under salt stress, improve the content of nutrition in rhizosphere soil, reduce the absorption of wheat for salt and promote the growth of wheat seedling. This suggests that Enterobacter sp. FYP1101 has a great potential in improving the adaptation of plant to stress.

Abstract:[Background] Anaerobic fungi can be inhibited by nitrovin. The presence of associated methanogens enhances the growth of anaerobic fungi and the decomposition of lignocellulose by anaerobic fungi. However, few studies have investigated the effect of the co-cultured methanogens on stress resistance of anaerobic fungi. [Objective] The objective of this study was to investigate the effect of associated methanogen on the resistance of anaerobic fungus to nitrovin. [Methods] Mono-culture of anaerobic fungus Piromyces sp. and co-culture of Piromyces sp. and Methanobrevibacter thaueri were inoculated into fresh media with rice straw as substrate, respectively. Nitrovin hydrochloride was added to the final concentrations of 0, 5, 10 and 25 mg/L-nitrovin. Bottles were incubated at 39 °C for 96 h without shaking. Gas production and methane production were measured at intervals. At the end of fermentation, the pH was determined immediately upon removing crimp-seals and stoppers. Samples were collected for the analysis of in vitro digestibility of dry matter, digestibility of neutral detergent fiber, digestibility of acid detergent solution and digestibility of acid detergent fiber. The water-soluble end-products including formate, lactate and acetate were measured as well. [Results] In the mono-culture, nitrovin (5, 10 and 25 mg/L) significantly reduced the fermentation activity of anaerobic fungus (P<0.05). In the co-culture, no significant difference was observed when adding 5 mg/L nitrovin (P>0.05). However, the fermentation activity was significantly depressed at the concentrations of 10 and 25 mg/L. At the concentrations of 5 and 10 mg/L nitrovin, the fermentation activity of the co-culture was significantly higher than the mono-culture (P<0.05). [Conclusion] A dose effect of nitrovin on the fermentation of anaerobic fungal mono-culture and co-culture was observed. The presence of associated methanogen enhanced the resistance of anaerobic fungus to nitrovin when the concentration of nitrovin was less than 25 mg/L.

Abstract:[Background] Storage is an important procedure of Chinese rice wine production. However, due to the rich nutrients, Chinese rice wine often appeared spoilage problems during storage process, resulting in huge economic losses. [Objective] The purpose of this study was to analyze the key microorganisms in spoiled Chinese rice wine by culture-independent and culture-dependent methods. [Methods] High-throughput sequencing technique was used to analyze the key microorganisms in the aging yellow rice wine of different origins. Specific culture medium was used to isolate and cultivate spoilage microorganisms in rice wine. Specific primers (Lactobacillus acetotolerans and Lactobacillus fructivorans according to the recA and tuf, respectively) were designed to identify the spoilage microorganisms. The isolated species were inoculated into non-spoiled rice wine to verify the spoilage ability. [Results] High-throughput sequencing results showed that Lactobacillus was the dominant genus (abundance>95%). And the abundance of two species (L. acetotolerans and L. fructivorans) was more than 82% at the species level. Thirty-six strains were successfully isolated on the designed culture media from spoiled rice wine. Twenty-eight strains of L. acetotolerans and eight strains of L. fructivorans were specifically identified by the specific primers of recA and tuf genes. The two main spoilage microbes were then inoculated into non-spoiled rice wine, and the acidity of the wine was improved significantly after two weeks. [Conclusion] High-throughput sequencing technology is a quick method for analyzing hard-to-culture microorganisms in food. Based on the combination of culture-independent and culture-dependent methods, we found that the key microorganisms that caused yellow rice wine spoiled were L. acetotolerans and L. fructivorans.

Abstract:[Background] Bacterial ghosts (BGs) are empty and intact bacterial envelopes of Gram-negative bacteria that are produced by controlled expression of the phage PhiX174 lysisE gene. BGs have higher biological safety, which can induce good systemic and mucosal immune response in a similar way of live bacteria. [Objective] To identify the pathogenic strain 16-3 isolated from the liver of large yellow croaker (Pseudosciaena crocea) with ulcerative disease and to generate bacterial ghosts from this strain by the temperature-controlled expression of cloned bacteriophage PhiXl74 lysis gene E. This study will provide an effective means to prevent and control the infection of Vibrio alginolyticus in aquaculture fish species. [Methods] Strain 16-3 was identified by morphological, physiological and biochemical characteristics and 16S rRNA gene sequence analysis. Temperature-controlled lysis plasmid pBV220-LysisE was constructed and then electroporated into V. alginolyticus strain 16-3 to form recombinant strain 16-3(pBV220-LysisE). Different initial concentration cultures of recombinant strain 16-3(pBV220-LysisE) were induced at 42 °C to compare the differences of lysis kinetics curves and lysis rate among them. V. alginolyticus strain 16-3 ghosts were generated under the optimum condition, and then their morphology and structure were observed by electronic microscope, and the viable cell counts in the lyophilized ghosts were measured using a pour plate method. [Results] The pathogenic strain 16-3 was identified as V. alginolyticus according to morphological features, physiological and biochemical characteristics and 16S rRNA gene phylogenetic analysis. The temperature-controlled lysis plasmid pBV220-LysisE and recombinant V. alginolyticus strain 16-3(pBV220-LysisE) were constructed, respectively. The optimum conditions for V. alginolyticus strain 16-3 ghosts generation were as follows: the induction was carried out by selecting the initial concentration of cultures reached an OD600 of 0.3. The bacterial ghosts could be harvested after induced for 3 h and the lysis rate of strain 16-3 ghosts was 96.9%. However, there was no residual bacteria found on plates with lyophilized 16-3 ghosts inoculation. Electron micrographs clearly showed that no gross alterations in cellular morphology compared to unlysed cells except for the obvious lysis pore on the cell surface and cell shrinkage due to the loss of cytoplasmic materials. [Conclusion] V. alginolyticus strain 16-3 ghosts were generated in this study, which provided a basis for the further use as a vaccine or vaccine delivery vector.

Abstract:[Background] Vibrio anguillarum is the main pathogen of marine animal vibriosis, which exists widely in seawater. It can form biofilm to adapt to environmental changes and form self-protection, the prevention and treatment of Vibrio anguillarum is a major challenge to aquaculture industry. [Objective] To study the characteristics of biofilm formation of pathogenic Vibrio anguillarum BYK0638, and to provide a reference for further study on the mechanism and pathogenesis of biofilm formation of V. anguillarum. [Methods] The characteristics of biofilm formation of V. anguillarum BYK0638 were studied by modified microtiter-plate test, and the viability of V. anguillarum in the biofilms was detected by CCK-8. [Results] V. anguillarum BYK0638 developed stable and evident biofilm on the surface of the polystyrene microtiter plate. OD450 value of V. anguillarum biofilm reached the peak after 24 h and stabilized after 60 h. Within the 107?108 CFU/mL, OD450 vaule of biofilm was significantly higher than the others (P<0.05). OD450 value of biofilm recorded at 25 °C was significantly higher than those recorded at other temperatures (P<0.05). In the range of pH 4.0?11.0, when pH value is 7.0, the amounts of bacterial biofilm was the highest, and at pH 3.0 and 12.0, no evident biofilm was found. Biofilm formation of V. anguillarum played no significant role when 0.03 to 2.00 mmol/L CaCl2 was added. Addition of 0.03% MgCl2 significantly promoted the bacterial biofilm formation while CaCl2 played no significantly role. At 5% NaCl, the OD450 value of biofilm was the highest. The biofilms developed on the surface of the microtiter plate coated by the skin mucus, liver, foregut and hindgut tissue extract of large yellow croaker was significantly higher than the others (P<0.05). [Conclusion] Pathogenic V. anguillarum BYK0638 can develop stable and obvious biofilm. The biofilm formation is closely related to the change of environmental factors, pH, temperature, Mg2+, salinity and other environmental factors can significantly affect the formation of biofilm of V. anguillarum.

Abstract:[Background] Hygrocins, a kind of naphthalene ansa antibiotics, are potential leading compounds for the chemical biosynthesis of novel drugs. However, under the common medium and fermentation conditions, the content of Hygrocin A in the cell is generally very low, and it is difficult to detect it directly. [Objective] In order to improve the yield of Hygrocin A from Streptomyces hygroscopicus ATCC 29253. [Methods] Effects of carbon source, nitrogen source, phosphate concentration, MgCl2 concentration, NaCl concentration and seed age on Hygrocin A production from S. hygroscopicus ATCC 29253 were studied by single factor and orthogonal test design. [Results] The optimal fermentation conditions were as follows: glucose 4.0 g/L, soybean cake meal 8.0 g/L, malt extract 10.0 g/L, K2HPO4 1.5 g/L, KH2PO4 1.5 g/L, NaCl 1.5 g/L, MgCl2 1.0 g/L; seed age 48 h; culture parameters: shaking speed 200 r/min, pH 6.8?7.0, bottled in 50 mL/250 mL, inoculated quantity 5%, incubated at 30 °C for 10 days. Under optimized conditions, the yield of Hygrocin A increased 500%, compared with its original medium M10, whereas at the same time the yield of Rapamycin decreased 95%. [Conclusion] The yield of Hygrocin A from S. hygroscopicus ATCC 29253 was significantly improved by optimizing the fermentation medium, which lay the foundation for studying the synthesis and application of Hygrocin A. At the same time, the yield of Rapamycin decreased significantly. This suggests that the metabolic flux of the two antibiotics can be adjusted intentionally by selecting the culture conditions, and then the metabolic regulation research for simultaneous expression of multiple antibiotics can be carried out.

Abstract:Biofilm is a predominant lifestyle for microbes, in which microbial communities adhere to surfaces and are embedded in an extracellular matrix. Regulating the biofilm formation process on surfaces to meet practical demands is of great importance. Herein, we introduced the mechanism of biofilm formation on surfaces along with its key factors. The effects of surface properties, including surface charge, wettability, roughness, topographic patterns, and functional chemical modifications, on bacterial adhesion and biofilm formation were summarized in detail. Finally, we reviewed the research progress in material preparation for inhibiting or enhancing biofilm formation according to different application scenarios.

Abstract:Metabolomics studies the complete biological system, to detect target or non-target metabolites by appropriate analytical methods and to interpret metabolites in combination with statistical models. Microalgae studies focus now increasingly on molecular mechanism by means of metabolomics. Here, we summarize the development of metabolomics, the research process and the characteristics of common analytical techniques and the progress of metabolomics in the field of microalgae. We also discuss the prospect of metabolomics in microalgae research, and challenges in practical application.

Abstract:Short branched-chain fatty acids and short branched-chain alcohols (SBCFAs and SBCAs, C4?6) serve as versatile platform chemicals for the chemical industry. They are commonly used as starting materials or building blocks to produce a wide range of valuable end products in chemical, food and pharmaceutical industries. Therefore, there is a huge demand for such platform chemicals in the global market. Currently, SBCFAs and SBCAs are predominantly produced through traditional chemical synthesis. However, these chemical conversion processes are heavily dependent on fossil fuels and always lead to serious environmental pollution. Moreover, the efficiency of these processes is often low. Recently, rapid developments in metabolic engineering of microbes provide a promising alternative to produce these platform chemicals. These bio-based manufacturing systems using microbial cell factories will help move the industrial production of SBCFAs and SBCAs towards more sustainable, environmentally friendly and economically competitive. Here, we reviewed the current status of metabolic engineering of microbes that produce SBCFAs and SBCAs including microbial hosts, key enzymes, metabolic pathways and engineering of SBCFA/SBCA biosynthesis. Furthermore, key challenges and future perspectives were discussed.

Abstract:To study phylogenetic relationships of endophytic nitrogen fixing bacteria in plants, common methods include morphology and protein level identification, numerical classification and automatic identification, chemical classification and identification, and molecular genetic identification. This paper introduces the key techniques of common methods, and discusses their advantages and disadvantages. With the development of high-throughput DNA sequencing technology in the field of microbiology, the whole genome sequencing has been applied to the study of microbial phylogenetic evolution. However, there is no systematic review of nitrogen-fixing endophytes whose genomes have been sequenced. A preliminary study on measuring whole genome sequences of endophytic diazotrophs. Several representative new methods based on genomic data (ANI analysis, the maximal unique match index, core genome analysis, component vector method, gene flow analysis) were summarized. Based on the current research methods of phylogenetic evolution, research trends of the development and evolution of Endophytic Nitrogen Fixing Bacteria were summarized and prospected. The purpose of this paper is to make the phylogenetic evolution of Endophytic Nitrogen Fixing Bacteria more accuracy and reliability.

Abstract:Brucellosis is a zoonotic and contagious infectious disease caused by infection with Brucella species, threat to livestock and human healthy seriously. Prevent and eliminate to brucellosis is significant to public health security and development of breeding industry. However, the pathogenic mechanism and relative virulence factors are not clear due to the facultative intracellular pathogen and complex construction for Brucella. In addition, brucellosis vaccine are all smooth strains currently in China, leading interfere with natural infection, which cause the seriously difficult for purification. Most of research had not preferable result due to these problems. Proteomic is a new method which is developing gradually to study constitutes and disciplinarians of proteins, the researches have increased to reveal the pathogenesis and immunologic mechanism of Brucella, and supplied a new way to solve above problems. Based on the author’s own research in this field, this paper makes a summary on research progress of proteomic in the brucellosis research for seek the specific proteins and differential diagnosis methods.

Abstract:Glycopeptide antibiotics have potent inhibition of gram positive bacteria. They are also as the last line of defense for dealing with the serious infections caused by such bacteria. As the drug-resistant pathogens spread, the application of glycopeptide antibiotics becomes more and more restricted. In this review, the structural characteristic of glycopeptide antibiotics and their structure-bioactivity relationship, the mechanism of biological activity and resistance for pathogenic bacteria of glycopeptide antibiotics were summarized. Furthermore, the biosynthetic mechanism and targeted generation of novel glycopeptide antibiotics by synthetic biology strategy for clinical application was also discussed.?Finally, the problems in the glycopeptide antibiotic application were prospected.

Abstract:Combined with the characteristics of “problem setting” and “problem solving” of Problem-based learning (PBL) method, a novel teaching model suitable for the experimental courses was developed based on the theories of Flipped classroom. Taking the practical problem of “water is suspected of being contaminated by feces” as an example, the innovative teaching design and application was explored for the course of Environmental Biology Experiment, which is one of the basic courses for environment specialty undergraduate in higher education. The teaching model was carried out as followed: pre-class preparation, class implementation and after-class feedback. In the pre-class preparation process, the teaching team need to set up a number of related experimental scenarios for the practical problem, prepare the teaching resources such as teaching video, and arrange students to learn and complete the self-learning tasks. During the class, students were directed to perform experiment, observe and record the results, and were inducted to how to think by asking questions. After class, students were required to submit the experiment reports, to complete the consolidation exercises and feedback the problems. The practice showed that this PBL teaching model based on flipped classroom was successful and was worth promoting.

Abstract:[Background] The morphology and genome between Aspergillus flavus and A. oryzae were highly similar, which made it very difficult to distinguish with each other. [Objective] The aim of this study was to establish an accurate method for distinguishing A. flavus with A. oryzae. [Methods] Twenty-two standard strains were used to study the five traditional identification methods of A. flavus and A. oryzae, including the traditional morphological identification method, enzyme linked immunosorbent assay (ELISA), the toxin-secreting culture medium method, the phylogenetic tree method and the detection method for toxin genes. [Results] There are differences or complements among the results of different methods. [Conclusion] A single method used to distinguish the two species would have a potential risk, while a polyphasic approach could resolve this problem.