凝结芽孢杆菌抗葡萄糖分解代谢物阻遏突变株合成培养基的筛选和发酵特性研究

Study on Screening of the Chemically Defined Media and Fermentation Characteristics of Bacillus coagulans Anti-carbon Catabolite Repression Mutant

以实验室前期选育的耐高温菌凝结芽孢杆菌Bacillus coagulans HL5-C以及其突变株5E-1为研究对象,筛选适合两菌株生长和代谢的合成培养基并对其发酵特性进行研究。单因素添加实验结果表明,合成培养基中尿嘧啶是影响HL5-C生长的关键物质,而赖氨酸、脯氨酸和苯丙氨酸则是影响5E-1生长的关键因素,由此分别得到了适合于HL5-C和5E-1生长的合成培养基MCDM4和MCDM5。在此基础上,考察了HL5-C和5E-1在单一碳源和混合碳源条件下的发酵情况,结果表明当非速效碳源与葡萄糖共存时,出发菌株HL5-C优先利用葡萄糖,其他糖的利用被延滞,即出现了碳源分解代谢物阻遏效应(carbon catabolite repression,CCR);突变株5E-1在利用葡萄糖的同时还利用非速效碳源生产乳酸,说明5E-1能消除碳源利用顺序的差异,即5E-1能有效解除或缓解葡萄糖引起的分解代谢物阻遏。本文研究结果为后续凝结芽孢杆菌葡萄糖分解代谢物阻遏效应机制研究奠定了基础。

The thermotolerant Bacillus coagulans HL5—C and its mutant 5E—1 were selected as the research objects.The chemically defined media(CDM)suitable for the growth and metabolism of HL5-C and 5E-1 was screened and their fermentation characteristics were studied.The single factor addition experiment results showed that uracil in chemically defined media was the key substance affecting the growth of HL5-C in CDM,while lysine,proline and phenylalanine were the necessary components for 5E-1 growth.The CDM suitable for HL5-C and 5E-1 growth was named MCDM4,MCDM5,respectively.Then,the fermentation conditions of HL5-C and 5E-1 under single carbon source and mixed carbon source were investigated,it was found that HL5-C preferentially utilized glucose and the utilization of other non-glucose sugars was delayed,showing carbon catabolite repression(CCR).However,5E-1 produced lactic acid by metabolizing glucose and other non-available carbon sources simultaneously,which indicated that 5E-1 could effectively relieve or alleviate CCR induced by glucose.The results laid a foundation for CCR mechanism research in B.coagulans.