Introduction of single-use multi-bioreactor system with full control functions for pH, dissolved oxygen, and temperature of individual bioreactors

Abstract

Quorum sensing is the response-regulation system of genes expression in accordance with the variation of cell population density. In this communication system, the response-regulation system induces group behaviors via signal molecules, which enabling cell acts actively to external environmental fluctuation. From practical point of view, these group behaviors ubiquitously occurred in a myriad of environments threatening human health and causing unrecoverable deterioration of manufacturing processes.Therefore, the mechanism of quorum sensing involves producing, releasing, detecting, and responding to small hormone-like chemical compounds called as autoinducers. For intraspecies communications, Gram-negative bacteria representatively utilize acyl-homoserine lactones, and Gram-positive bacteria typically use modified peptides as autoinducer. In case of a eukaryote, fungi generate a variety of autoinducers, such as farnesol, tyrosol, and aromatic alcohols. The intraspecies quorum sensing allows bacteria themselves to recognize the same species in the mixed culture system, but it could not use to detect the presence of other species and identify and act on their proportions in the overall environmental system. Thus, bacteria produce furanone-based signal molecules to build an interspecies communication and maintain a balance in the entire ecosystem. This type of bacterial Esperanto, called autoinducer-2, is synthesized by LuxS protein and its associated genes have been found in over 70 different microorganisms to date. Meanwhile, recent studies also identified that interkingdom quorum sensing between eukaryote and prokaryote, such as a bacteria-to-fungi, bacteria-to-plant, and bacteria-to-mammalian cell. This chapter focuses on the history of quorum sensing and the signal molecules chemistry; how response-regulation system in bacteria is developed; how the definition of quorum sensing is determined; how the signal molecule is generated; and the recent studies related to the exploration of new quorum sensing systems.