Interactions Between Bacillus Licheniformis And Saccharomyces Cerevisiae And Their Application In Liquor Fermentation

Chinese liquor fermentation is a typical natural fermentation process， which ischaracterized by fermentation in an open environment，sorts of various microorganism’sinteraction and fermentation leads to the final unique liquor style. Therefore，one of the keysto understanding the essence of food fermentation is the comprehension of the interactionsbetween microorganisms. The study of microbial interactions plays an important role for theresearch of the mechanisms of liquor brewing and fermentation technology development，thesuccessful studies of functional microbial interactions in the domain of foreign fermentationfood also proved this point.By building the co-culture system of B. licheniformis and S. cerevisiae under liquidfermentation conditions，its interaction was investigated combined the actual fermentationconditions such as inoculation ratio，temperature and other factors. We also applied S.cerevisiae and B. licheniformis at different ratio in the fermentation process of Sesame-flavorliquor and Maotai-flavor liquor, and tracked the microbial interactions and the dynamicchanges of bacteria and yeast community structure during the fermention process.The result indicated that1) In order to analyze the microbial community in the fermentation process of Chineseliquor, the interaction as well as its mechanism of two important microorganisms, Bacilluslicheniformis and Saccharomyces cerevisiae was studied. Research showed that the growth ofB. licheniformis could be inhibited by S. cerevisiae in the coculture system even theinoculation ratio of S. cerevisiae and B. licheniformis is1:10000. Further study showed thatexcept the acidic environment caused by the yeast, S. cerevisiae could also produce certaininhibitors which is sensitive to heat and protease that can inhibit the growth of B.licheniformis. In the co-culture system, though the growth of B. licheniformis was inhibited, itcan promote the2-methyl butyric acid and4-vinylguaiacol produced by S. cerevisiae; and theinoculation ratio adjustment of strains can effectively improve the flavor production functionof B. licheniformis.2) Optimized the inoculation quantity of S. cerevisiae in the Sesame flavor liquorfermentation process. Research indicated that the diversity of bacteria structure were similarwhen inoculated S. cerevisiae at1×10~5and2×10~5CFU/g fermented grains; althoughbacteria community structure didn’t have a significant change, the1×10~5CFU/g inoculationquantity of S. cerevisiae leads to the lower content of alchols and esters in liquor; in contrast,when the yeast inoculation quantity up to5×10~5CFU/g, the growth of B. licheniformis willbe inhibited and the structure of bacteria diversity decreased.3) The dynamic changes of bacteria and yeast community structure and the aromacomponent of soy-sauce flavor liquor were investigated when the bacteria inoculum wasimproved. Study showed that2‰percentage inoculation of bacteria can significantly increasethe B. licheniformis proportion in the bacteria structure, also caused the diversification ofyeast community structure in the fermentation process. The liquor alcohols, acids, esters and other flavoring component on the total content did not change significantly, but different aromacomponent’s content were regulated, making the liquor more prominent in soy-sauce flavor.