Quorum sensing blockade in Pseudomonas aeruginosa: biodegrading of N-Acyl homoserine lactone by Bacillus cereus UT26 and its consequent effects on their interaction

Bacteria use a chemical language to communicate with each other which enables them to synchronize gene expression as a result of cell density. This special language which is called quorum sensing (QS) is based on producing and sensing the small signals and eventually leads them to perceive when a minimum population unit is reached. On the contrary, quorum sensing blockade (quorum quenching) has been recently grabbed scientists attention as a promising tool in controlling bacterial pathogens which utilize N-acyl homoserine lactone (AHL) to regulate their virulence factor production. Biodegradation of AHL molecules is an efficient way in QS interrupting which normally happens in the natural environment. In this survey, the effect of Bacillus cereus UT26 strain as an efficient quorum quencher on degrading both signal molecules (C4-HSL and 3oxoC12-HSL) of Pseudomonas aeruginosa was investigated. The strain strongly degraded both AHLs and hereby inhibited pyocyanin production in the lab condition. Moreover, co-culture experiments revealed that quorum quenching activity has an important role in interaction between different bacterial species; since the wild type (wt) strain of B. cereus UT26 reached 1000 fold higher growth yield comparing aiiA mutant strain of which has lost quorum quenching activity by a site directed mutation in AiiA lactonase gene.