枯草芽孢杆菌lspA影响细菌型豆豉中四甲基吡嗪的合成研究

Bacillus subtilis BJ3-2 lspA Affects the Synthesis of Tetramethylpyrazine in Bacterial-type Douchi

枯草芽孢杆菌是细菌型豆豉中主要的微生物,其代谢产物四甲基吡嗪(Tetramethylpyrazine,TTMP)为一种具有坚果香气的风味活性化合物。为探究枯草芽孢杆菌脂蛋白信号肽酶Ⅱ(LspA)对豆豉中TTMP含量的影响。本研究以枯草芽孢杆菌BJ3-2为研究对象,利用同源重组敲除载体,构建BJ3-2ΔlspA菌株,并检测其中α-乙酰乳酸合酶与α-乙酰乳酸脱羧酶基因的转录水平;在45℃,用BJ3-2ΔlspA发酵大豆72 h,定量检测吡嗪类化合物和乙偶姻。结果表明,相比BJ3-2,BJ3-2ΔlspA中α-乙酰乳酸脱羧酶基因的转录水平显著下调0.51倍;吡嗪类物质含量显著下降,TTMP和乙偶姻的含量分别降低了46.65%和14.42%。本文首次报道了lspA对TTMP合成的重要作用,为豆豉风味调控提供理论基础。

Bacillus subtilis is the main microorganism of Bacterial-type Douchi,the metabolite tetramethylpyrazine(TTMP)of B.subtilis is a nutty aroma flavor active compound.To explore the effect of B.subtilis lipoprotein signal peptidase II(LspA)on TTMP content in Douchi.In this study,B.subtilis BJ3-2 was used as the research object,BJ3-2ΔlspA was constructed using a knockout vector by homologous recombination.The transcriptional levels ofα-acetolactate synthase andα-acetolactate decarboxylase genes were detected.Pyrazines and acetoin were quantified in fermentation soybeans by incubation with BJ3-2ΔlspA for 72 h at 45℃.The results showed that compared with BJ3-2,the transcript level ofα-acetolactate decarboxylase gene in BJ3-2ΔlspA was significantly down-regulated by 0.51-fold.The content of pyrazines was significantly decreased,and the content of TTMP and acetoin were reduced by 46.65%and 14.42%,respectively.This paper reports for the first time the important role of lspA on TTMP biosynthesis,and provides a theoretical basis for the flavor regulation in Douchi.