N -acyl-homoserine lactone quorum sensing switching from acidogenesis to solventogenesis during the fermentation process in Serratia marcescens MG1

• Published in: Journal of microbiology and biotechnology
• Main Authors: Jin, Wensong, Lin, Hui, Gao, Huifang, Guo, Zewang, Li, Jiahuan, Xu, Quanming, Sun, Shujing, Hu, Kaihui, Lee, Jung-Kul, Zhang, Liaoyuan
• Format: Journal Article
• Language: English
• Published: Korea (South) 28.02.2019
• Subjects: N-acyl-homoserine lactone quorum sensing; acidogenesis; solventogenesis; Serratia marcescens MG1; switch
• ISSN: 1738-8872

-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 noticeable decrease by approximate 30% for acetoin during 32-48 h and by 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.