老化窖泥己酸代谢的研究

Caproic acid metabolism pathway of aged pit mud

浓香型白酒的独特风味与窖泥有着密不可分的关系,而以己酸为前体物质的己酸乙酯是浓香型白酒中最重要的香气成分。该实验采用宏转录组技术对产己酸关键酶基因crt1、bcd、etfA1、etfB1、hbd1、nfnA和nfnB在老化窖泥中的表达以及老化窖泥中的己酸代谢途径进行了研究,为白酒品质提升提供理论依据。结果表明,根据关键酶基因的物种注释结果,推测脱卤厌氧杆菌(Anaeromyxobacter dehalogenans)可能是窖泥中一类重要微生物;同时,窖泥中己酸的合成可能并非己酸菌作用的结果,而是由多种非己酸菌共同作用产生。在老化窖泥中,D-乳酸和L-乳酸之间不能通过乳酸消旋酶相互转换,丙酮酸通过丙酮酸氧化还原酶或2-氧代酸氧化还原酶而不是丙酮酸甲酸裂解酶催化生成乙酰辅酶A。

The unique flavor of Luzhou-flavor Baijiu(Chinese liquor)is closely related to pit mud.Ethyl hexanoate,which is the precursor of hexanoate,is the most important aroma component in Luzhou-flavor Baijiu.The expression of key enzyme gene crt1,bcd,etfA1,etfB1,hbd1,nfnA and nfnB that produced caproic acid in aging pit mud and the pathway of caproic acid metabolism in aged pit mud were studied by macro transcriptome technique,which provided a theoretical basis for Baijiu quality improvement.The results showed that Anaeromyxocharacter dehalogenans might be an important microorganism in pit mud according to the results of species annotation of key enzyme genes.Besides,the synthesis of caproic acid in pit mud may not be the result of the action of caproic acid bacteria,but produced by a variety of non caproic acid bacteria.In aged pit mud,D-lactate and L-lactate could not be converted to each other by lactate racemases.Pyruvate is catalyzed by pyruvate oxidoreductase or 2-oxo-acid oxidoreductase instead of pyruvate formate lyase to produce acetyl coenzyme A.