SCREENING AND IDENTIFICATION OF NEW GENES INVOLVED IN THE QUORUM SENSING SYSTEM

Abstract

Quorum Sensing (QS) is an important cell-cell communication system that allows bacterial cells to recognize their own population density by sending and detecting extracellular signals. These signals are recognized by outer membrane receptors and alter the expression of specific genes, regulating a wide variety of important biological functions. The molecules involved in this communication may be also detected by other bacterial species and plants, inducing a modulation of their gene expression, metabolism and growth. In response to interspecific detection ability of these molecules, the Quorum Quenching (QQ) system evolved. The QQ is involved in the general control of the physiology of bacterial populations. The QQ molecules interfere with cell-cell communication by degrading the QS molecules. The QQ system is important in niches in which different bacterial populations compete for resources, since the capacity for detection of QS molecules of other bacterial species is an adaptive advantage and is often found in many Bacillus species. The present project aims to find new genes related to the QQ system in soil metagenomic libraries, including those previously described as having new genes related to QS systems. The report of the active QS in this library strengthens the hypothesis of the presence of new genes related to the QQ system too. However, unlike the QS system studies with QQ molecules are more recent and much less numerous, especially when we observe the low number of genes described as related to the QQ system. Thus, this work will contribute to better understanding of the diversity and genetic structure of this mechanism.