Novel insights on the bacillus quorum sensing mechanism: Its role in competence, virulence, sporulation and biofilm formation

Abstract

A large number of Bacillus sps are ubiquitous and can modulate in diverse environments. The QS response in Bacillus sp. involves expression of adaptive extracellular factors like food-degrading enzymes, virulence factors, antibiotics, or biosurfactants. They produce QS signals as small peptide molecules i.e. autoinducer peptides (AIP) processed from their oligopeptide precursors. Members of the Rap-Phr family of QS systems in Bacillus subtilis are involved in regulation of competence, sporulation and biofilm formation. Moreover they possess a typical Com QXPA QS system which controls the expression of nearly 200 genes, including both extracellular and intracellular factors. However in B. thuringenesis, the virulence expression, sporulation and nectotropism are strongly regulated by NprR/ NprX signal regulators which belong to RNPP family. NprR/NprX QS system was identified to regulate the expression of pathogenesis in B.anthracis, which causes fatal pulmonary infection. Two established QS systems PlcR/PapR and NprR/NprX for virulence regulation were found in different species of Bacillus. Current review emphasizes on the comparative study of different QS systems in Bacilli which control the pathogenesis and development processes. Despite the fundamental biological importance in medicine and industry, Bacillus QS molecules can serve as potential biomarkers.