清香型白酒立醅期酒醅中主体酸和细菌菌群结构动态解析

Dynamic analysis of main acids and bacterial flora structure in the Fen-flavor fermented grains during LiPeiQi

为了解立醅期清香型白酒发酵过程中乳酸、乙酸含量的变化规律以及酒醅中细菌菌群结构随发酵时间的变化情况,从酒醅中分离出产酸能力强的优势产酸菌株,采用高效液相色谱技术分析立醅期清香型白酒酒醅大楂和二楂阶段乳酸、乙酸含量的变化情况,通过HiSeq高通量测序技术分析酒醅中细菌菌群结构随发酵时间的变化规律,从MRS培养基中分离筛选出产酸能力强的乳酸菌株,并对该菌株的环境耐受性进行进一步研究。在立醅期2个月的发酵过程中,大楂和二楂的乳酸、乙酸含量呈波浪形上升趋势,且在二楂发酵阶段,乳酸、乙酸的初始含量与酒醅大楂时期出缸时的主体酸含量基本一致;酒醅中的乳酸含量远远高于乙酸含量且二楂酒醅中的主体酸含量高于大楂酒醅;另外,二楂酒醅乳酸与乙酸的比值也始终高于大楂酒醅。乳杆菌属在发酵过程中的菌群结构变化情况与乳酸含量变化相一致,尤其在发酵后期该菌属相对丰度显著升高。从发酵后期的酒醅样品中筛选得的5个产乳酸微生物中,棒状腐败乳杆菌Lactobacillus coryniformis和嗜酸片球菌Pediococcus acidilactici具有较强的产酸能力和耐酸、耐醇能力。该研究对清香型白酒酒醅在立醅期的主体酸含量变化和菌群结构动态变化进行了研究,为之后的微生物代谢改造提供了基本的信息,筛选出的菌株对改善清香型白酒的风味口感具有潜在应用价值。

In order to analyze the change of lactic acid and acetic acid contents and the bacterial flora structure in fermented grains during the fermentation of Fen-flavor Baijiu in LiPeiQi,and to isolate the stronger acid-producing strains from fermented grains.This paper analyzed the change of lactic acid and acetic acid contents in the Fen-flavor fermented grains during LiPeiQi at the stage of DaCha and ErCha by HPLC,and analyzed the changes of bacterial flora structure in fermented grains during the fermentation of Fen-flavor Baijiu by HiSeq high-throughput sequencing,then the strains with strong ability that produced lactic acid was isolated and screened by MRS medium.Further,the environmental tolerance of the strain had been studied.The contents of lactic acid and acetic acid at both DaCha and ErCha showed a wavy upward trend during the two-month fermentation period,and the initial contents of lactic acid and acetic acid in ErCha were basically the same as the main acids contents of the fermented grains at the time of leaving the vat during DaCha.In addition,the ratio of lactic acid to acetic acid in ErCha was always higher than that in DaCha.The change of flora structure of Lactobacillus during fermentation were consistent with the change of the lactic acid content.In the late fermentation period,the relative abundance of Lactobacillus increased significantly.Among the five strains of lactic acid-producing microorganisms screened from the late fermentation grains,Lactobacillus coryniformis and Pediococcs acidilactici could produce acid strongly.Also,that strains could tolerate acid and alcohol strongly.The change in lactic acid and acetic acid contents and in bacterial flora structure of fermented grains during the fermentation of Fen-flavor Baijiu in LiPeiQi provided basic information for microbial metabolic transformation later,and the screened strains have potential value for improving the flavor and taste of Fen-flavor Baijiu.