Metabolic dependent and independent pH-drop shuts down VirSR quorum sensing in Clostridium perfringens

Publication date: Available online 17 January 2018 Source:Journal of Bioscience and Bioengineering Author(s): Keika Adachi, Kaori Ohtani, Michio Kawano, Ravindra Pal Singh, Basit Yousuf, Kenji Sonomoto, Tohru Shimizu, Jiro Nakayama Clostridium perfringens produces various exotoxins and enzymes that cause food poisoning and gas gangrene. The genes involved in virulence are regulated by the agr-like quorum sensing (QS) system, which consists of a QS signal synthesis system and a VirSR two-component regulatory system (VirSR TCS) which is a global regulatory system composed of signal sensor kinase (VirS) and response regulator (VirR). We found that the perfringolysin O gene (pfoA) was transiently expressed during mid-log phase of bacterial growth; its expression was rapidly shut down thereafter, suggesting the existence of a self-quorum quenching (sQQ) system. The sQQ system was induced by the addition of stationary phase culture supernatant (SPCS). Activity of the sQQ system was heat stable, and was present following filtration through the ultrafiltration membrane, suggesting that small molecules acted as sQQ agents. In addition, sQQ was also induced by pure acetic and butyric acids at concentrations equivalent to those in the stationary phase culture, suggesting that organic acids produced by C. perfringens were involved in sQQ. In pH-controlled batch culture, sQQ was greatly diminished; expression level of pfoA extended to late-log growth phase, and was eventually i...
Source: Journal of Bioscience and Bioengineering - Category: Biomedical Science Source Type: research