The Isolation And Identification And Physiological And Biochemical Characteristics Of Acetic Acid Bacteria In Fermented Grains Of Feng-flavor Liquor

To investigate the diversity of acetic acid bacteria in Xifeng fermented grains, strainswere isolated by the traditional culture-based technique. and their characteristics weredetermined by16S rDNA PCR-RFLP, aicd production, utilization of sole source carbon andnitrogen. Their phylogentic relationship was revealed through sequence analyses of16SrRNA genes. The results were showed as follows:The number of acetic acid bacteria increased at the beginning of fermentation, thendecreased to stable level at last. In the first ten days, the acetic acid bacteria displayed a rapidgrowth to the highest peak, up to3×107cfu/g. During the10d to15d, the number declinedsharply. At the later period of fermentation (15d~21d), acetic acid bacteria remaines stable.Based on the combined result of the PCR-RFLP and phologenetic analysis of16S rRNA,46tested strains were classified into three genera, including Acetobacter, Weissella andMethylobacillus. Among them, Acetobacter pasteurianus was the predominant groupaccounting for89.13%of all strains. Strain AC1was closely related to the type speciesWeissella cibaria with100%sequence identity of16S rDNA. Strain AC7was closely relatedto Acetobacter pasteurianus with99.71%sequence similarity. Strain AC11, AC18wasrelated to Acetobacter pasteurianus with the sequence similarity99.63%and100%,respectively. Strain AC37was closely related to Methylobacillus flagellatusare a sequencesimilarityof99.93%.Four representative strains showed the assimilation capacity to glucose, sucrose,maltose, citric acid, glycerol as the sole carbon source, but they could not use amylum,D-galactose, lactose and L-rhamnose monohydrate as the sole carbon source. They alsoutilized L-leucine, tyrosine, L-asparagine, L-cystine as the sole nitrogen source, however they were unable to utilize L-glutamate as the sole nitrogen source.The ethanol tolerance of Acetobacter spp. in range from5%to11%v/v was detectedduring acetic acid production. High alcohol content can prohibit the acid-production. Eachstrain has different capacity to resist alcohol in the medium.The study will provide microbial resources and new way to improve the quality of liquorin the process of production.