Spatial Heterogeneity Of Prokaryotic Microorganism Communities In Luzhou-flavor Liquor Pit Mud

Luzhou-flavor Liquor fermentation is a typical solid state fermenting process whichproceeding in the opening-natural environment. Various micro-organisms, came from air,water, material, da qu and mud pit, take part in the process of saccharification and liquorfermentation. Pit mud is the most important component of mud cellar, the structure ofmicrobial communities in it is closely related to the production of flavor compounds in theliquor. Furthmore, the difference of environmental factors in top, middle and bottom layerwould lead the different of microbial communities in the pit mud and there is differentmetabolism in mud cellar. So, it is very impotant to using the theory of microbial ecology tounderstand the fuction of pit mud in the process of liquor fermentation.In recent years, along with the development of the biological technology, detecting thespatial heterogeneity of community structure in the pit mud by molecular biology has been anefficient way to analyze the liquior fermentation and its aroma-mechanism. In this study, totalDNA was extracted from the microorganism of each sample which collected from top, middleand bottom layer of mud cellar, respectively, and the16S rRNA metagenomic libraries werebuilt for sequence analysis. The results showed that the capacity of bacterial metagenomiclibraries were that:83of recombinant clones for top,131of recombinant clones for middle,101of recombinant clones for bottom layer. The capacity of archaeal metagenomic librarieswere that:79of recombinant clones for top,108of recombinant clones for middle,85ofrecombinant clones for bottom layer. The sequence analysis of each samples showed that thevariability of class group and quantity of bacteria in the pit mud was observed obviously.Clostridium diolis and Lactobacillus acetotolerans were the two dominant communities in thepit mud, the percentage of them from top layer to bottom layer were34.9%and39.8%、25.2%and20.6%、23.8%and36.6%, respectively. Bacillus subtilis subsp. Subtilis was also one ofthe dominant communities which had a ratio of22.1%in mid layer. The community ofArchaea which was mainly constructed with Methanoculleus sp. and Methanosarcina sp. wassimple. Methanoculleus bourgensis was the dominant community in top layer and bottomlayer, the percentage of it in the two places were89.9%and88.2%, respectively.Methanosarcina siciliae and Methanoculleus bourgensis were the dominant communities inmid layer and the percentage of them were40.7%and49.1%, respectively. Phylogeneticanalysis shows that, Bacilli, Clostridiales, Enterobacteriales and some bacteria like TM7phylum sp., which the classification were not clear, were the main class of bacteria in the pit mud. Methanomirobiales and Methanosarcinales were the main class of Archaea in the pitmud.Analyzing with the production experience, according to the variability of prokaryoticmicrobial community and the quantity of recombinant clones detected in this study, wo thinkthat, the variability of aroma-mechanism in different regions of the pit mud is not only relatedto the metabolic activity of microorganism in one fermenting turn, but also related to thefators such as the status of Zao pei, the quality of Huang shui and the accumulation of aromamaterials, etc. This study provides the scientific basis for detecting the flavor formationmechanism of Luzhou-flavor liquor, and has important guiding significance forLuzhou-flavor liquor production and quality control.