Isolation And Identification Of Lactic Acid Bacteria From Vinegar Fermenter Daqu

The traditional brewing process of Shanxi Daqu of Shanxi Mature contains many microorganisms and enzymes involved in their activities,their common activities lead to the unique flavor of Shanxi vinegar.Daqu is the saccharification and fermentation agent for Shanxi vinegar,Shanxi vinegar brewed with mildew,bacteria and yeasts and other microorganisms.Lactic acid of Shanxi vinegar vinegar in accounted for 70%-80%of non-volatile acids,and the non-volatile acid content accounts for 1/3 of the total acid.So lactic acid bacteria is essential for Shanxi vinegar fermentation process,which is one of the important types of microorganism.In order to separate the lactic acid bacteria more quickly and easily from Shanxi vinegar Daqu,This study was designed to add inhibitors to conventional MRS media,A selective medium was designed for the isolation of lactic acid bacteria from complex microbial communities.Doing experiment with known fungi,isolated from Daqu yeast,Bacillus subtilis,acetic acid bacteria and lactic acid bacteria,to determine the dosage of each inhibitor,while suppressing bacteria at the same time,to ensure the growth and amount of target lactic acid bacteria.Finally,the lactic acid bacteria in Daqu of Shanxi vinegar were isolated by the selective medium,the strains were identified by 16S rDNA combined with colony morphology and Gram stain observation.The test results are as follows:(1)Through the observation of colony morphology and colony count,effect of treatment group1 is preferable,namely adding sorbic acid in MRS culture medium for 1000mg/L,natamycin 10mg/L.That is,add sorbic acid 1000mg/L,natamycin 10mg/L.This medium inhibited test mold,yeast,bacillus and most of the acetic acid bacteria growth in the MRS medium,and did not inhibit the growth of the tested lactic acid bacteria(2)With the design of selective medium,lactic acid bacteria were isolated from Daqu,according to the colony characteristics,no plate molds and yeasts appeared,selecting 68 colonies randomly,the results showed that the purified gram for gram positive cocci,according to the individual morphology and colony morphology,Twenty-three strains(numbered L1-L32),which were different from each other,were selected for identification.To determine whether it is lactic acid bacteria.16S rDNA sequence analysis showed that L13 is Corynebacterium lactis,and the rest is Papillococcus.Indicating that the selected selection medium can separate lactic acid bacteria from complex samples efficiently,and the predominant lactic acid bacteria in the sample Daqu are Pediococcus pentosaceus.