Jin Wensong, Lin Hui, Gao Huifang, Guo Zewang, Li Jiahuan, Xu Quanming, Sun Shujing, Hu Kaihui, Lee Jung-Kul, Zhang Liaoyuan
College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, P.R. China.
Gutian Edible Fungi Research Institute, Fujian Agriculture and Forestry University, Gutian 352200, P.R. China.
J Microbiol Biotechnol. 2019 Apr 28;29(4):596-606. doi: 10.4014/jmb.1810.10026.
-acyl-homoserine lactone quorum sensing (AHL-QS) has been shown to regulate many physiological behaviors in MG1. In the current study, the effects of AHL-QS on the biosynthesis of acid and neutral products by . MG1 and its isogenic with or without supplementing exogenous -hexanoyl-L-homoserine lactone (C-HSL) were systematically investigated. The results showed that disruption resulted in rapid pH drops from 7.0 to 4.8, which could be restored to wild type by supplementing C-HSL. Furthermore, fermentation product analysis indicated that could lead to obvious accumulation for acidogenesis products such as lactic acid and succinic acid, especially excess acetic acid (2.27 g/l) produced at the early stage of fermentation, whereas solventogenesis products by appeared to noticeably decrease by an approximate 30% for acetoin during 32-48 h and by an approximate 20% for 2,3-butanediol during 24-40 h, when compared to those by wild type. Interestingly, the excess acetic acid produced could be removed in an AHL-QS-independent manner. Subsequently, quantitative real-time PCR was used to determine the mRNA expression levels of genes responsible for acidogenesis and solventogenesis and showed consistent results with those of product synthesis. Finally, by close examination of promoter regions of the analyzed genes, four putative box-like motifs were found upstream of genes encoding acetyl-CoA synthase, lactate dehydrogenase, α-acetolactate decarboxylase, and Lys-like regulator. The information from this study provides a novel insight into the roles played by AHL-QS in switching from acidogenesis to solventogenesis in . MG1.
酰基高丝氨酸内酯群体感应（AHL-QS）已被证明可调节MG1中的多种生理行为。在本研究中，系统地研究了AHL-QS对MG1及其同基因菌株在添加或不添加外源己酰基-L-高丝氨酸内酯（C-HSL）的情况下酸和中性产物生物合成的影响。结果表明，基因敲除导致pH值从7.0迅速下降至4.8，补充C-HSL可将其恢复至野生型水平。此外，发酵产物分析表明，基因敲除会导致产酸产物如乳酸和琥珀酸明显积累，尤其是在发酵初期产生过量乙酸（2.27 g/l），而与野生型相比，基因敲除菌株的溶剂生成产物在32 - 48小时内乙偶姻减少约30%，在24 - 40小时内2,3-丁二醇减少约20%。有趣的是，产生的过量乙酸可以通过与AHL-QS无关的方式去除。随后，使用定量实时PCR来确定负责产酸和溶剂生成的基因的mRNA表达水平，结果与产物合成结果一致。最后，通过仔细检查分析基因的启动子区域，在编码乙酰辅酶A合成酶、乳酸脱氢酶、α-乙酰乳酸脱羧酶和类赖氨酸调节因子的基因上游发现了四个假定的盒状基序。本研究的信息为AHL-QS在MG1从产酸转变为溶剂生成过程中所起的作用提供了新的见解。
