Analysis On Microbial Communities In Chinese Luzhou-flavor Liquor Pits

During the fermentation of Luzhou-flavor liquor, the formation and the changes of microbial communities decide the metabolisms of materials and energy in zaopei, and are connected with the formation of special trains of Luzhou-flavor liquor. For a long period, because of the disperse research condition and backward technologies, researchers know very limited about the microbial communities in zaopei during fermentation. In this research, we examined the changes of microbial communities in zaopei of Luzhou-flavour liquor in the aspects of time and space by using clone analysis, DGGE, etc., modern molecular biology methods. The results of this research as following, 1) At the beginning of fermentation, yeasts were dominant in top layer and middle layer, any microbe in bottom layer has a quantity lower than 103/g; for the first wee, after fermentation began, the quantities of yeasts, aerobic bacteria and anaerobic bacteria in top layer and mid layer increase greatly, the quantity of aerobic bacteria and anaerobic bacteria in bottom layer increased greatly too; after fermented for 14 days, the quantities of yeast, aerobic bacteria and anaerobic bacteria all decreased; after fermented for 21days, the quantity of every microbe was lower than 104/g, anaerobic bacteria became dominant microbes gradually. The quantity of mold in top layer and middle layer kept at a high level during the first week of fermentation, then decreased gradually, then increased for a short time, then decreased; the quantity of mold in bottom layer increased greatly during the first week of fermentation, then decreased suddenly, after fermented for 14 days, the quantity of mold in bottom layer keep at the level of 102/g. Through analysis, no obviously differences were found to the compose of microbes in the zaopei from the same layer. 2) To the analysis of bacteria in zaopei, Bacillus, Lactobacillus, Lactococcus, Streptococcus, Clostridium, Staphylococcus, Microbacterium, Arthrobacter, Erwinia, Acetobacter, Kozakia, Granulicatella, Shewanella, Unclassified Clostridiales (miscellaneous), etc., altogether more than 13 genera of bacterium were detected. They focused on Bacillales, Lactobacillales, Actinomycetales, Clostridiales, Rhodospirillales, etc., 5 orders. Among these bacteria, Erwinia, Kozakia, Granulicatella and Shewanella haven't been reported that they were detected in Zaopei of Luzhou-flavour liquor and fermented grains yet. In the 0-day-fermented samples, the bacteria belong to genus Clostridium and some bacteria belong to Unclassified Clostridiales are dominant bacteria. Most bacteria under order Clostridiales can decompose organic substance to organic acid, alcohols, CO2/H2, and minerals, they always were reported that forming commensal group with methane bacteria and they can't be cultivated or difficult to cultivate, including some butyric acid bacteria and caproic acid bacteria, they may relate to the creation of butyric acid, caproic acid, ethyl butyrate and ethyl caproate by hydrolyzing starch. After fermented for 1 week, the bacterium under genus Lactobacillus that has a similarity of 98% with strain Lac.acetotolerans was dominant bacterium. This bacterium might play a key role in the fermentation of Zaopei and the formation of special traits of Luzhou-flavour liquor. 3) To the analysis of yeast, Saccharomyces, Oosporidium, Brettanomyces, Citeromyces, Pachysolen, Hansenula, Dekkera, Saccharomycopsis, Issatchenkia, Trichosporon, Torulaspora, Zygosaccharomyces, etc., altogether 12 genera of yeasts were detected. These yeasts mainly appeared in prophase fermented Zaopei, and genus Issatchenkia yeast was dominant yeast. Genus Issatchenkia yeast may play a key role in alcohol fermentation in prophase. 4) To the analysis of mold, Aspergillus, Neurospora, Mucor, Talaromyces, Penicillium, Eurotium, Fomitopsis, etc., altogether 7 genera of molds were detected. GenusTalaromyces molds were dominant molds in prophase. It might answer for the saccharification of starch and its quantity decreased greatly in metaphase. At the end of fermentation, the quantity of Genus Talaromyces molds increased in the Zaopei which taken from the edge of middle layer, and became dominant molds, they might have the functions of saccharifying starch and digesting fibre. In metaphase and telophase, genus Eurotium became dominant mold genus, it may have the function of digest starch and polysaccharide and esterification of alcohol. Through the analysis of microbes in Zaopei during fermentation, the fermentation procession of microbes in Zaopei was discribed as following, In prophase, with the assistance of a part of yeasts, the molds under genus Talaromyces completed the saccharifycation of starch. At the same time, the yeasts under genus Issatchenkia began proliferating. With the assistance of other yeasts, the yeasts under genus Issatchenkia completed alcohol fermentation. The bacteria mainly under genus Clostridium and unclassfied Clostridiales proliferated highly in prophase. During this period, great deals of acetic acid, butyric acid, lactic acid and caproic acid, etc. organic acid were created. These organic acids were the material of esterification. Bacterium under genus Lactobacillus was dominant bacterium in metaphase and telophase, besides closely connected with the formation of it might the formation of ethyl lactate, it might play a key role in the formation of special traits of Luzhou-flavour liquor. Talaromyces genus and Aspergillus genus molds may play key roles in saccharification of starch in metaphase and telophase. Genus Eurotium molds may play key roles in esterification.