Chapter 3 - Microbial communications in Gram-positive and Gram-negative bacteria

Abstract

Bacterial gene expression is regulated by density dependent cellular communication known as quorum sensing (QS) for expression of various virulence factors and secondary metabolites during stress conditions. Both Gram-positive and Gram-negative bacterial species communicate with one another with the help of small signaling molecules. The regulatory machineries that are present in canonical signaling pathway have novel regulatory network designs. The Gram-positive cells mainly communicate with the help of small peptides known as autoinducer peptides or quorum sensing peptides. The Gram-negative groups of bacterial cells communicate by N-acyl homoserine lactone molecules. QS molecules are found not only to maintain interactions between the bacterial species but are associated with the cross talks existing within the host. Various types of peptides and chemical compounds are associated with the bacterial communications. Such communication accentuates competence, virulence, production of antibiotics, sporulation, motility, and formation of biofilm. Interference of QS by stalling signal generation is not very common, although effective quorum quenching can stop this communication.