Evidence-based validation of quorum quenching from Lysinibacillus sphaericus and Geobacillus sp. in bioremediation of oil sludge.

Abstract

Many studies on quorum quenching focus on the discovery and characterization of novel acyl-homoserine lactonases (AHL-lactonases) because these enzymes could be used in the control of diseases caused by Gram-negative bacteria. The effects of quorum quenching are also remarkable in the performance of bacterial consortia in applications such as bioremediation. In the current work, we demonstrated the presence of a potential novel AHL-lactonase-encoding locus (Bsph_3377) from Lysinibacillus sphaericus and Geobacillus sp. The deduced amino acid sequences for this enzyme possess the characteristic domains and motifs involved in Zn-binding from AHL lactonases and were grouped into 1 clade within the phylogeny of the lactonases from firmicutes, showing 70% of identity with the lactonase AhlS from Solibacillus silvestris. We demonstrated the locus transcription by RT-qPCR and its relationship with the suppression of the pathogenicity of Pectobacterium carotovorum. Additionally, we analyzed the interaction of these bacilli with a commercial consortium in the bioremediation of a hydrocarbon-contaminated soil, showing inhibitory effects on its establishment. These results represent a new contribution in the understanding of the potential biotechnological applications of L. sphaericus and Geobacillus sp. as well as in the research on antibacterial techniques based on quorum-sensing disruption.