Communication mechanisms in extremophiles: Exploring their existence and industrial applications.

Quorum sensing plays important roles in the regulation of physiological and virulence processes in most bacteria, but its role in extremophiles is largely unknown. Comparative genomic, phylogenic, structural and signaling pathways analyses and deletion mutant studies have suggested the presence of three major quorum sensing systems (AI-1, Peptide based and AI-2) in extremophiles. Autoinducer-1(AI-1) system was found to be most prevalent (except in thermophiles where it is autoinducer-2) while peptide based system was least prevalent in extremophiles. Some unknown mechanisms of quorum sensing have also been reported which need further exploration. Quorum sensing is utilized by extremophiles for processes like cold adaptation, lowering the freezing point, biofilm formation, oxidative stress resistance and persister cell formation. Explication of quorum sensing in extreme environments may provide discernment regarding the role and functional strategies for survival of extremophiles. Here the role of quorum sensing in different classes of extremophiles and also in their survival strategies has been reviewed. Further, the applications and problems caused by quorum sensing regulated factors in extreme environments are discussed.