Study On The Diversity Of Microbe Of The Pit Mud In Shi-li-xiang Liquor And Screening And The Application Of Microbe Producing Hexanoic Acid

In the production of Luzhou-flavor liquor,the quality of pit mud directly affects the liquor quality.Ethyl hexanoate is the main aroma of Luzhou-flavor liquor,which is formed by esterification and dehydration of caproic acid and ethanol.In this paper,the pit mud of Shi-li-xiang liquor and spirits in Cangzhou,Hebei Province was taken as research object to analyze its diversity of microorganisms and the strain with high yield of caproic acid was selected.The following of this paper focused on the characters of acid-producing and made the obtained hexanoic acid-producing clostridium into the pit mud curing liquid for pit mud maintenance.Major contents of this study were included:?1?By collecting samples of pit mud from Shi-li-xiang liquor and spirits in Cangzhou,Hebei Province,The microbial diversity of pit mud was analyzed by High-throughput sequencing.From the graph of abundance grades,we can know that the community uniformity of sample YB2 and YS2 was better than other samples.In all samples,sample B and D are basically the same in terms of diversity of bacterial flora,and were superior to sample S.From the perspective of taxonomic composition analysis,The dominant bacteria in the pit mud at different locations are mainly Firmicutes at a phylum level,and the common dominant bacteria in the sample was Aminobacterium?10.7%-30.8%?at a genus level.?2?The Clostridium with high-yielding hexanoic acid producing was selected from the high-quality pit mud of Shi-li-xiang,which has a fermentative hexanoic acid producing ability of about 1136.4 mg/L.After molecular biological identification,it was determined that the strain is Clostridium kluyveri.The optimal acid-producing culture conditions for Clostridium kluyveri are 35?,90%liquid loading,pH value in a range of 6-7,2%ethanol,2%glucose,and 0.05%ammonium.?3?An isolated and purified Clostridium kluyveri SLXJNR3-1 was prepared into bacteria solution for pit mud maintenance.A single-factor and orthogonal test methods were used to optimize influencing factors for preparation of pit mud maintenance bacterial solution,and the optimal propagation conditions for the strains were determined as 2%glucose,0.04%KH₂PO₄,0.02%MgSO₄,0.5%NaAc,0.05%?NH₄?₂SO₄,0.1%yeast extract,2%ethanol,2×10^-7%biotin,pH 6.6,32°C.The cell growth kinetic model of the strain was established with this parameter,and then the cultured bacterial solution was used for pit mud maintenance and strengthening.The content of hexanoic acid-producing bacteria in the pit mud of the experimental group was increased by 36%compared with the control group,and hexanoic acid in the original wine was increased,the content of ethyl ester increased from 3475.5 mg/L to 4375.8 mg/L,and the quality of pit mud and raw wine was significantly improved.