Roles of quorum sensing molecules from Rhizobium etli RT1 in bacterial motility and biofilm formation.

Strain RT1 was isolated from root nodules of Lens culinaris (a lentil) and characterized as Rhizobium etli (a Gram-negative soil-borne bacterium) by 16S rDNA sequencing and phylogenetic analysis. The signaling molecules produced by R. etli (RT1) were detected and identified by high-performance liquid chromatography coupled with mass spectrometry. The most abundant and biologically active N-acyl homoserine lactone molecules (3-oxo-C8 -HSL and 3-OH-C14 -HSL) were detected in the ethyl acetate extract of RT1. The biological role of 3-oxo-C8 -HSL was evaluated in RT1. Bacterial motility and biofilm formation were affected or modified on increasing concentrations of 3-oxo-C8 -HSL. Results confirmed the existence of cell communication in RT1 mediated by 3-oxo-C8 -HSL, and positive correlations were found among quorum sensing, motility and biofilm formation in RT1.