Microbial Diversity And LAB Biofilm In Xinjiang Traditional Fermented Milk

In this study,we used high-throughput pyrophosphate sequencing to investigate the microbial community diversity and the microbial diversity of three kinds of culture medium in traditional fermented milk samples from the Atux and Uqturpan in Xinjiang.To explore the Lactic acid bacteria biofilm formation ability in traditional fermented milk,the samples were analyzed by pure culture,96 well micro-plate semi-quantitative methods and scanning electron microscopy.Finally,by the Physiological and biochemical experiments and 16 S rDNA sequences were analyzed of the biofilm-formation strains.Pyrosequencing produced a total of 165201 high quality bacterial 16 S rRNA gene sequences and 407365 fungul high quality reads from the 10 traditional fermented milk samples from Atux and Uqturpan.At the bacterial level,Sequence analysis grouped the high quality gene sequences into seven bacterial phyla,of wich Firmicutes wre the dominated and the Protiobacteria was subdominant phylum.The bacteria detected 43 different genera,of wich Lactobacillus and Streptococcus wre the dominated.At the fungal level,Sequence analysis grouped the high quality gene sequences into five fungal phyla,the prodiminant phyla were Ascomycota(80.08%)and Basidiomycota(10.87%)in samples A4,Ascomycota(46.03%)and Zygomycota(53.97%)in samples U7,prodiminant phyla were Ascomycota in other samples,wich accounted for 97.33-99.95% of the population.The fungal detected 43 different genera,of wich Kluyveromyces and Saccharomyces were dominanted.By high-throughput pyrosequencing to investigate the diversity of culturable microorganism on the MRS?YGC and Lee shi culture medium of traditional fermented milk from three samples of Atux and one sample of Uqturpan,under the laboratory condition.Results showed that,Firmicutes and Ascomycota wre the dominated in all samples,Basidiomycota,Zygomycota,Ascomycota are widely present in all samples,but the content is less.At the bacterial level,Lactobacillus was the dominant species in the sample 1.Lactobacillus,Streptococcus and Acetobacter were dominant in sample 3 and sample 7,of which lactobacillus was dominant.At the fungal level,Saccharomyces and Kluyveromyces were dominated in four samples,and richness wre higher compared to other samples in AM1,AM3,AL4 and UM7.Also identified low abundance genera,such as Sebacina,Mortierella,Aspergillus,Candida,Alternaria sp in fermented milk.3By the pure cultured method 57 strains of bacteria and 78 strains of yeast were isolated from four samples,The micro-plate semi-quantitative method was used to investigate biofilm formation of bacteria.Results showed that 37(73.68%)of the LAB strains showed biofilm formation ability,of which 16(28.07%)strains are strongly adhered to biofilm strains and 22(38.59%)were moderately adherent biofilm strains,other 19 strains were cant form biofilm.Using a scanning electron microscope(SEM),the representative strains of strong adhesion biofilm bacteria,moderately adherent bacteria,and non-adherent biofilm-forming bacteria were used for electrophysiological images.Results showed that,the strongly adhered to biofilm bacteria colony gathered together,the surface of bacteria-dense,colony thickening,gathered into groups and formation of large biofilm.Moderately adherent bacteria colony a small part,began to adhere and gather,wrapped in metabolites,colony between the larger gap.And non-adherent biofilm-forming bacteria,bacterial cells adhere to very little,compared to strong adhesion biofilm bacteria and moderately adherent bacteria have a significant difference.Analyzed for the biofilm-formation strains by the Physiological and biochemical experiments and 16 S rDNA sequences.Results showed that 38 strains were tested for catalase-negative;Can not use sorbitol and rhamnose;Can use glucose to produce acid can not produce gas;Can not hydrolyze xylose;except for 23,37,M65,L20,120 strains can't use lactose,other strains of lactose hydrolysis capacity is strong.Except for 76 nuber bacteria can not use sucrose,other strains of sucrose,fructose hydrolysis ability is strong.16 S rDNA sequence analysis showed that,the strains which can form biofilm were belonging to three species of six genera,in which Enterococcus.Durans(15strains),Enterococcus.Faecium(3strains),Enterococcus.Thailandicus(7strains),Enterococcus.Lactis(2 strains),Lactobacillus.Plantarum(6 strains),Streptococcus.thermophilius(5strains),of which Enterococcus is the dominant species and Lactobacillus and Streptococcus was subdominant species.