Abstract:The members of the genus Cellulomonas exhibit distinct advantages in degradation of cellulose owing to their producing varieties of cellulases. In 1923, Bergey established the genus Cellulomonas with Cellulomonas flavigena as the type species. Later, the family Cellulomonadaceae was proposed by Stackebrand and Prauser with Cellulomonas as the type genus in 1991. Up to date, there are 26 validly described species in this genus, which were isolated from different environments. The typical taxonomic characteristics of the genus Celluomonas included:possessing Orn and Glu/Asp as the peptidoglycan components in the cell wall; MK-9(H₄) as the predominant methylquinone; anteiso-C_15:0 and C_16:0 as the main fatty acids and diphosphatidylglycerol and phosphatidylinositol mannoside as the main polar lipids. The G+C content of genomic DNA is 68.5-76.0 mol%. Recently, the taxonomic status of two newly isolated strains of the genus Celluomonas was determined by the means of polyphasic taxonomy in our laboratory. In this review, we summarized the establishment and taxonomic characteristics of the genus of Celluomonas. As well, the application prospects of the Celluomonas spp. in environmental protection and enzyme resources were reviewed.

Abstract:[Objective] We isolated and identified a cadmium resistant bacterium from activated sludge. Furthermore, we studied its growth characteristics and optimal biosorption conditions of Cd²⁺. This study was expected to provide strain resources and applied reference for microbial remediation of cadmium contaminated water.[Methods] The bacterium was isolated by streak plate and identified based on its 16S rRNA analysis, hemolysis testing and protein crystallization dying experiment. The growth conditions of the strain were determined by single factor test. The optimal biosorption conditions of bacterial powder were investigated by designed orthogonal experiment. Besides, the biosorption mechanisms were discussed by Scanning electron microscope (SEM), Energy Dispersive X-ray Scanning (EDS) and Fourier transform-infrared spectroscopy (FTIR) analysis. [Results] The strain was identified as Bacillus cereus and named as H6. The maximum cadmium tolerance concentration of strain H6 was 350 mg/L. Its culture conditions were:initial pH 6.0 to 8.0 at 28℃, shaking speed of 120 to 210 r/min, inoculation 1% to 5%. During the growth of strain H6, the pH of culture medium first decreased slightly and then increased gradually. The optimal biosorption conditions of bacterial powder were:dosage of 0.125 g/L, contact time of 2 h, pH 5.0 and 30℃, the biosorption capacity reached 205 mg/g. SEM-EDS and FTIR results revealed that ion exchange between Ca²⁺and Cd²⁺ occurred and the functional group of hydroxyl, carboxyl, carbonyl, amido and alkyl played a principal role during the biosorption process. [Conclusion] Strain H6, isolated from the activated sludge, was identified as Bacillus cereus with good adsorption property for Cd²⁺.

Abstract:[Objective] The Surugamides (sgm) biosynthetic gene cluster has been reported to contain four NRPS genes surA-D which give two unrelated NRPS pathways. It was experimentally confirmed that surA and surB were essential for Surugamide A and Surugamide F production respectively. However, the functions of surC and surD genes are not verified with experimental evidence. This work is designed to confirm if surA and surD genes are responsible for Surugamide A biosynthesis so as to pave the way to either genetically engineering of Surugamides biosynthetic pathways or study the recognition mechanism of their NRPS proteins. [Methods] The Actinomycetes isolated from marine sponge were identified by analyzing their 16S rRNA gene sequences. The natural product biosynthetic gene clusters were analyzed by submitting genomic sequences to the online database antiSMASH. The chemical structures of isolated compounds were elucidated by UPLC-Q-TOF-MS and ¹³C NMR. To generate the mutation of gene deletion and replacement, a plasmid was constructed with two fragments used for target homologous recombination. The plasmid was then transformed into the target strain for screening of double-crossover mutants. [Results] We discovered Surugamides gene cluster from the genome of Streptomyces albidoflavus LHW3101 isolated from marine sponge Dactylospongia elegans. The compound Surugamide A and Surugamide F were then identified from the fermentation extract of the strain. The surB and surC gene in Surugamides gene cluster were replaced with a constitutive and strong promoter ermEp^*, which was located just before the transcription frame of surD gene. The resulted mutant RJ9 lost the production of Surugamide F but kept on producing Surugamide A with around two-fold yield of the wide type strain.[Conclusion] Gene surB and surC are verified to be not related to sgm A production. It is reported that surA is essential for Surugamide A production. And a remarkable yield improvement for Surugamide A was achieved after introducing a strong promoter before the open reading frame of surD in this work. Therefore we concluded that surA and surD take charge of the biosynthesis of Surugamide A.

Abstract:[Objective] To investigate the effect of N-glycosylation on the enzymatic properties of β-glucosidase Bgl3A from Talaromyce leycettanus. [Methods] Site-directed mutagenesis was conducted to construct three N-glycosylation-removing mutants T44A, S228A and S299A, and the gene products were expressed in Pichia pastoris GS115. [Results] In comparison with wild type Bgl3A, the mutant S228A was low in protein secretion, with trace activity against pNPG, while mutants T44A and S299A showed similar optimal pH and temperature, i.e. pH 4.0 and 75 ℃, but had higher T_m values and greater thermostability at 70℃. When using pNPG as the substrate, mutants S299A and T44A had decreased catalytic efficiencies (k_cat/K_m) of 14.5% and 70%, respectively; for cellobiose, T44A retained almost the same catalytic efficiency, while S299A showed an improvement of 1.1-fold. [Conclusion] N-glycosylation modification at different sites of Bgl3A had different effect on the secretion and enzymatic properties. Among them, S228 is essential for maintaining the expression and function of the enzyme, whereas S299 can increase the enzyme thermostability and catalytic efficiency on cellobiose.

Abstract:[Objective] We isolated and identified the natural products with antibacterial activity from fungal strain WH4-2.[Methods] We identified strain WH4-2 by colonial morphological traits and ITS sequence analysis, used activity-oriented method to isolate secondary metabolites, elucidated structures by spectrographic analysis, adopted micro-dilution method to assay antibacterial activity. [Results] We identified strain WH4-2 as Talaromyces stipitatus. Activity-oriented separation resulted in the isolation of compound 1 (5S-arugosin K), 2 (5R-arugosin K), 3 (5S-arugosin M), 4 (5R-arugosin M) and 5 (Chrysophanol), Compounds 1 through 4 were elucidated as isopentenyl dibenzo[b,e] oxepinone, compound 5 was anthraquinone. Compounds 1 through 4 showed potent antibacterial activities against S. aureus ATCC43300, ATCC33591, E. faecium ATCC35667 and B. subtilis ATCC6633.[Conclusion] The antibacterial compounds isolated from fungus T. stipitatus were isopentenyl dibenzo[b,e] oxepinone enantiomers.

Abstract:[Objective] The aim of this study was to isolate microorganisms capable of degrading polyethylene materials, for example, agricultural mulch film. [Methods] By culturing the fungal strains with liner low-density polyethylene powder, we obtained a fugal strain with the ability of polyethylene degradation. Then we identified this strain by cultivation characters and molecular biology methods. Furthermore, we tested the degradation efficiency of agricultural mulch film of the fungus, weight loss of mulch, Fourier Transform infrared spectroscopy (FTIR) spectrogram and high-resolution field emission scanning electron microscope. [Results] Fungus PT1 capable of degrading agricultural mulch film was identified as Penicillium citrinum. PT1 could grow on linear low-density polyethylene powder with an average molecular weight of 2000 or 400000 as the sole carbon source. It could degrade low-density polyethylene powder and corrode traditional polyethylene film monitored by FTIR spectrogram and high-resolution field emission scanning electron microscope. The weight loss of polyester biodegradable film is about 50% after 35 days when co-cultured with PT1 strain. [Conclusion] A new fungus strain to degrade agricultural mulch film, P. citrinum PT1, was isolated and identified. Our finding provides a new friendly way to deal with agricultural mulch film.

Abstract:[Objective] To construct a fast, convenient and economical DNA manipulating toolkit for gene deletion and marker recycling in Candida albicans. [Methods] By using Exo Ⅲ-mediated ligase-independent cloning strategy, loxP sites were inserted into the flanking regions of heterologous selection markers CmLEU2, CdHIS1, and CdARG4, yielding the templates for marker cassettes amplification. The Tet-on promoter was assembled using a rTetR element which was codon-optimized and chemically synthesized. Codon-optimized recombinase Cre was placed downstream of the Tet-on promoter. Then this cassette was inserted into the CDS region of selection markers CdHIS1 and CdARG4, generating vectors for marker recycling. [Results] We constructed three loxP-flanked marker gene-containing vectors for gene deletion in C. albicans, and two vectors for marker recycling, containing the recombinase gene Cre under the control of the Tet-on promoter. [Conclusion] We successfully constructed an inducible gene deletion and marker recycling vector system in C. albicans, which was practically applied in gene deletion strain constructions. This system is helpful to construct single and multiple gene deletion strain constructions.

Abstract:[Objective] Clostridium kluyveri genome encodes for three highly homologous thiolases. To identify the function of these three thiolases will help us to understand how Clostridium kluyveri can efficiently produce hexanoate. [Methods] The characteristics of hexanoate and butyrate production were examined via fermentation kinetics analysis. The transcriptome and reverse transcription-quantitative RCR were used to analyze the expression profiles of thiolase-encoding genes during fermentation. Thiolases from Clostridium kluyveri were heterologously expressed in Escherichia coli and their enzyme kinetic parameters were examined. [Results] Clostridium kluyveri produced butyrate, hexanoate and octanoate, of which hexanoate was the major product. Transcription analysis showed that thlA1 gene was constitutively expressed, thlA2 gene was up-regulated and thlA3 gene was down-regulated before the depletion of acetate. The three thiolase-encoding genes all had higher transcription levels, and the highest expression levels of thlA2 and thlA3 were approximately 29% and 43% that of thlA1, respectively. The enzyme kinetic parameters with four-carbon substrate demonstrated that the three thiolases from Clostridium kluyveri had similar affinity. However, the catalytic efficiency (k_cat/K_m) of ThlA1 for four-carbon substrates was lower than that of ThlA2 and ThlA3. [Conclusion] All of the three thiolases from Clostridium kluyveri had catalytic activities, and also actively expressed in vivo.

Abstract:[Objective] This study was to investigate the effect of a fermented feed on colonic fermentation and microflora of finishing pigs. [Methods] Capillary column gas chromatography was used to measure volatile fatty acid (VFA) concentration. Illumina MiSeq platform was used to detect community structure and diversity of the microflora of colonic mucosa and digesta. [Results] Fermented feed had no significant effect on microbial diversity of colonic mucosa and digesta (P>0.05), while increased the relative abundance of Weissella and Faecalibacterium in colonic mucosa (P<0.05). The relative abundance of Weissella and Subdoligranulum was higher in colonic digesta (P<0.05) compared with the control group. No significant difference was observed in pH, lactate, acetate, propionate, isobutyrate, valerate, isovalerate and total VFA concentration between the two groups (P>0.05), whereas butyrate concentration was greater in the treatment (P<0.05). [Conclusion] Fermented feed could affect the composition of colonic microflora and promote the formation of colonic butyric acid in finishing pigs, which could improve their intestinal health.

Abstract:[Objective] DNA-based stable isotope probing (DNA-SIP) is a powerful tool for tracing substrate assimilated microorganisms in complex environments. However, in recent studies involving SIP, we found that ¹³C utilization may interfere with experiment results. For example, when microcosm and DNA-SIP are applied to study straw degradation microorganism, ¹³C-labled straw is bound to be amended, but whether the amendment as well as the fertilization of soil will affect the microbial communities is still unknown.[Methods] We sampled three fertilized (Control, NPK, OM) paddy soil from Yingtan red soil ecological experimental station to study the difference of biogas emission, microbial diversity and responding species among three fertilized soils and two kinds of straw. Microcosms were conducted with ¹²C and ¹³C-labled straw amendments afterwards.[Results] We found that no difference of accumulative C emission was detected among three soils with ¹²C and ¹³C-labled straw amendments. Under oligotrophic (Control) conditions, soil bacterial communities of ¹³C-labeled treatment represented a higher diversity while microbial heterogenicity was higher in ¹²C-labeled treatment, and discrepant species were hardly detected between these two treatments. Under copiotrophic (NPK and OM) conditions, bacterial communities of ¹³C-labeled straw treatment performed no difference on both their diversity and structure, but discrepant species were detected, mainly belong to Proteobacteria and rare species. [Conclusion] Our results showed that ¹³C-labeled straw did affect bacterial communities to some extent. Hence, as labeling substrate, high abundance straw can be applied, but it need to be cautious in the following SIP experiments.

Abstract:[Objective] To find out the antibiotic resistance of 15 (1 β-lactam and 14 non-β-lactams) antibiotics and potential antibiotic resistance genes of Enterococcus faecalis, isolated from natural fermented food.[Methods] The antibiotic resistance of Enterococcus faecalis was detected with 15 antibiotics by micro broth dilution method. Then the genome-wide association study was applied to find the potential antibiotic resistance genes of Enterococcus faecalis by Scoary. [Results] This study showed that the 16 strains of Enterococcus faecalis were 100% sensitive to kanamycin, vancomycin, linezolid and erythromycin, but 100% resistant to clindamycin. In addition, the different degrees of antibiotic resistance to other antibiotics were showed in Enterococcus faecalis. The genome-wide association study found 9 potential antibiotic resistance genes, which were significantly correlated with 5 antibiotics (chloramphenicol, ciprofloxacin, trimethoprim, neomycin and tetracycline). Genes, including FAM000296 and FAM005768, were related to the resistance of chloramphenicol, trimethoprim and ciprofloxacin. FAM000296 and FAM005768 were both annotated as SecG, while compared to FAM000296, FAM005768 lost 21 bases at the 3 end. [Conclusion] Enterococcus faecalis isolated from natural fermented products is resistant to many antibiotics and carries potentially antibiotic resistant genes in its genome. Therefore, a comprehensive safety of Enterococcus faecalis should be assessed before application.

Abstract:[Objective] The distributions and relationships between crenarchaeol and chlorin were investigated in the continental shelf of East China Sea. [Methods] Organic chemical methods were used to extract crenarchaeol and chlorin from sediment samples. We used High Performance Liquid Chromatography/Mass Spectrometry to quantify crenarchaeol and High Performance Liquid Chromatography to quantify chlorin.[Results] We found that both crenarchaeol and chlorin were widespread in the continental shelf of East China Sea. Terrestrial inputs had little influence on either crenarchaeol or chlorin. Their absolute contents were correlated significantly (P<0.01) with each other. [Conclusion] The crenarchaeol and chlorin on the continental shelf of East China Sea both had marine origins rather than from terrestrial input. The abundances of crenachaeol and chlorin were correlated significantly, which suggested that crenarchaeol may be used as a potential index for the changes in the surface production of East China Sea during historical times.

Abstract:[Background] The waste drilling mud in the oil field has high oil content, complex pollutant and serious environmental hazards, and existing technologies cannot meet the requirements of the increasingly developed petroleum exploitation industry in the treatment of waste drilling mud. Biological treatment of waste drilling mud has the advantages of simple process and low cost, but it also has some limitations, including poor broad-spectrum, long processing cycle, low petroleum degradation rate and the fluctuation of sludge properties affects the active stability. [Objective] To improve the biological treatment of waste drilling mud, a microbial community with high activity and high environmental tolerance was constructed, and the comprehensive performance and genetic stability was analyzed. [Methods] Through directional enrichment, induction and acclimation methods, the efficiency of petroleum hydrocarbons emulsification and degradation was expected to be improved, and the feedback inhibition of co-metabolic substrate and quorum sensing system sensitivity were expected to be reduced. We analyzed the structure and the active members' types of the microbial community, and studied the corresponding relationship with emulsification-degradation of petroleum hydrocarbons. [Results] An active microbial community was enriched from drilling waste mud containing more than 12 g/kg oil, more than 80% aromatics-colliod-asphalt and more than 8 g/kg salt. The main members include Pseudomonas, Rhizobia, Rhodobacter and Dethiobacter alkaliphilus, with the ratio of 27.44%, 20.73%, 8.54% and 7.93%, respectively. During the continuous acclimation of more than 22 generations, the quantity of Pseudomonas, Alishewanella and Halomonas was accounted for more than 92.72%, the structure and activity of the microbial community was stable. When the waste drilling mud was treated for 5 days by the active community, the oil content of soil decreased from 12403 mg/kg to 42 mg/kg, the comprehensive oil removal efficiency was 99.67%, and the petroleum hydrocarbon degradation rate was 68.9%. The content in crude oil saturated soil was analyzed before and after microbial community action, the original oil content was 261 g/kg, and the oil content after treatment was 305 mg/kg, deoiling rate was 99.88%. [Conclusion] After acclimation, the microbial community has stable activity, strong tolerance to high salt environment, the active microbial community has strong industrial application potential in drilling waste mud, oily soil and sludge pollutant treatment.

Abstract:[Objective] The deposition of the airborne microorganisms and air pollution were closely related to the biodeterioration of the cultural heritage. In this study, a systematic survey of seasonal variation characteristics of bacterial concentration and community structure was carried out in the surrounding atmosphere of Maijishan Grottoes, a renowned cultural heritage site in China. The results will be helpful for the environmental monitoring and precaution of cave temples and preventive protection of cultural relics. [Methods] The Bio-aerosol sampler was used for sampling in all seasons in 2016. Traditional culture-based method to acquire the airborne bacterial concentration information and purified strains; by the extraction of genomic DNA, amplification of bacteria 16S rRNA region, sequencing, and phylogenetic analysis, thereafter the bacteria community composition and distribution characteristics were clarified. Combined with environmental monitoring data, to find out the main factors which may responsible for the dynamic changes of the airborne bacteria. [Results] The concentrations of culturable bacteria were in a range from 281.2 to 1409.2 CFU/m³, the highest and the lowest concentration appears at MJ4 in summer and at MJO in spring, which varied apparently with seasonal characteristics, but no significant difference among different sites. A total of 11 different bacterial genera that affiliated to four phyla were detected in this study, among which, Bacillus, Paenarthrobacter, Arthrobacter, Hymenobacter and Kocuria were dominant genera. [Conclusion] The airborne bacterial community structures of the Maijishan grottoes show a dynamic characteristic of the seasonal variation and spatial distribution; RH, temperature and rainfall all have influenced on the airborne bacteria distribution in different layers of the Grottoes; some of the genus, such as Bacillus and Micrococcus, has potentials that could result in the biodeterioration of the ancient wall paintings and painted sculptures at this site; the monitoring of the airborne bacteria in its surrounding atmosphere of the Maijishan grottoes may contribute to the grottoes conservation and tourism management.

Abstract:[Objective] The aim of this study was to isolate an efficient 3-phenoxybenzoic acid (3-PBA) degrading strain from the cabbage rhizosphere contaminated by pyrethroid pesticides. Furthermore, the co-degradation of beta-cypermethrin and soil bioremediation by co-culture of Bacillus licheniformis G-04 and 3-PBA-degrading strain were investigated. [Methods] 3-PBA-degrading strain was screened using enrichment domestication, isolation and purification methods, then identified by morphological, physio-biochemical tests and 16S rRNA sequence analysis. The growth and degradation kinetics of 3-PBA-degrading strain and B. licheniformis G-04 were analysised by Origin 8.0. The synergistic degradation ability and soils bioremediation of these two strains were evaluated by high performance liquid chromatography (HPLC). [Results] A novel 3-PBA-degrading strain HA516 was screened and identified as Acinetobacter pittii, the degradation rate of 3-PBA (100 mg/L) was 87.73% after 48 h of incubation. The growth and degradation kinetics of these two strains were established, which have the better fitting of predicted and the experimental value. When the inoculation proportion of the biomass of these two strains was 6.7:3.3, B. licheniformis G-04 was inoculated first, and A. pittii HA516 was inoculated after 24 h of cultivation, 78.37% Beta-CP (50 mg/L) was degraded at 48 h, which was 37.90% higher than only using strain B. licheniformis G-04, and half-life was shortened from 58.39 h to 24.51 h. Soil remediation test showed that the degradation rate of Beta-CP (30 mg/L) reached 79.27% on the seventh day, which was 33.26% higher than only using strain B. licheniformis G-04. [Conclusion] A. pittii HA516, a highly efficient 3-PBA-degrading strain, can be used as a potential strain resource for bioremediation of environment polluted with 3-PBA or pyrethroid pesticides. Beta-CP could be efficiently co-degraded by B. licheniformis G-04 and A. pittii HA516.

Abstract:[Objective] To screen an alginate-degrading strain and to improve the activity of its alginate lyase by optimizing the fermentation conditions.[Methods] A strain capable of degrading alginate was screened by the steps of enrichment culture, screening, and re-screening by using seawater and sea mud collected from the sea area of Zhangzhou (Fujian, China). Then, the strain was identified according to its 16S rRNA sequence analysis, physiological and biochemical characteristics, mycelium morphology and colony characteristics. The conditions of enzyme production of the strain were optimized by single factor and orthogonal test. [Results] The strain, belonging to the genus Cobetia marina, was named Cobetia marina HQZ08. The optimal medium of the strain was composed of 7.00 g/L sodium alginate, 3.00 g/L peptone, 30.00 g/L NaCl, 1.25 g/L K₂HPO₄·3H₂O. The optimal fermentation conditions were as follows:the optimum inoculum was 2%, the inoculation age was 12 h, the initial pH of the culture medium was 7.0, the culture temperature was 25℃, and the incubation time was 24 h. The enzymatic activity of alginate lyase reached 68.5 U/mL after optimization. Enzymatic hydrolysates were determined to be alginate oligosaccharides. [Conclusion] HQZ08 strain can be used to degrade alginate to produce alginate oligosaccharides with a degree of polymerization of 2-6.

Abstract:[Objective] The aims of this study were to analyze the compositional changes of bacterial community in Le'an River from upstream to downstream, and to reveal the main environmental factors shaping the bacterial community. [Methods] The hydrochemical indicators in different reaches, such as C, N, P, Cu, Zn, As and Pb, were measured. High-throughput sequencing of 16S rRNA gene was used to profile the bacterial community structure. Non-metric Multidimensional Scale (NMDS) Analysis and Cluster Analysis of sampling sites based on Bray-Curtis distance were used to explore the bacterial community structure along Le'an River. Redundancy analyzed (RDA) was used to analyze the relationship between environmental factors and bacterial communities. [Results] The concentrations of C, N, P, Cu, Zn, As and Pb were higher in the middle and lower reaches than those in the upper reaches. The diversity of bacterial communities decreased in the middle reaches because of the wastewater from the Dexing Copper Mine, and the richness and diversity increased in the lower reaches because of the wastewater from the agricultural and domestic wastewater. The predominant bacteria composition was Beta-proteobacteria (53.03%), Actinobacteria (20.24%) and Bacteroidetes (14.75%). Due to the influence of Dexing Copper Mine, the abundance of Beta-proteobacteria increased in the middle reaches, while the abundance of Actinobacteria decreased. In the lower reaches, the abundance of Bacteroidetes decreased due to the inter-microbial predation. In the relationship between the bacterial community and environmental factors, dissolved oxygen (DO) was the best environmental factor explaining the changes of bacterial community structure along the Le'an River. [Conclusion] Wastewater from the Dexing Copper Mine in the middle reaches of Le'an River and the agricultural and domestic wastewater in the middle and lower reaches changed the bacterial community structure, resulting the significant changes of the bacterial community along Le'an River. These findings provide a reference for revealing the influences of human activities on the water ecology of the Le'an River.

Abstract:[Objective] This study aimed to elucidate the bacterial community succession and its underlying relevance to the environmental factors in fermented grains of Luzhou-flavor baijiu. [Methods] The 16S rRNA gene amplicon sequencing analysis was applied to reveal the succession of bacterial community in the fermented grains, and Mantel test was used to correlate bacterial community succession with environmental factors. [Results] A total of 397 bacterial genera were identified in fermented grains, including Lactobacillus, Bacillus, Weissella, Dysgonomonas, Comamonas and Ruminococcaceae (relative abundance>1.0%). Fermentation process was divided into three stages:stage I (0-5 d), stage Ⅱ (6-17 d) and stage Ⅲ (18-40 d) according to clustering analysis, and the bacterial community structure was significantly different among these three stages. Metastats analysis demonstrated that the relative abundance of Lactobacillus and unclassified Lactobacillales in stage Ⅱ was significantly higher than that in stage I (P<0.05), whereas the situation of unclassified Bacillaceae, Staphylococcus, Bacillus, unclassified Enterobacteriaceae, Lactococcus, Pseudomonas, Thermoactinomyces, Leuconostoc and Staphylococcus quite the reverse (P<0.05). Compared with stage Ⅱ, the relative abundance of Lactobacillus increased in stage Ⅲ (P<0.05), conversely, downregulation dominated Comamonas, Acetobacter, unclassified Bacilli, Clostridium, Bacillus, Ruminococcus, unclassified Porphyromonadaceae and unclassified Streptophyta (P<0.05). Results of Mantel test indicated that the bacterial community succession in the stage I was correlated with the dynamics of temperature, moisture, and alcohol concentration (P<0.05), whereas no significant correlation was observed between environmental factors and bacterial community succession in the stage Ⅱ and Ⅲ (P>0.05). [Conclusion] Our work demonstrated the dramatically divergent bacterial community structure in the fermented grains of Luzhou-flavor baijiu from different brewing stages. Temperature, moisture and alcohol concentration significantly correlated with the bacterial community succession in early stage of fermentation (0-5 d).