QsdS lactonase from Sphingopyxis sp. strain EG6 inhibits biofilm formation by Pseudomonas putida strain TS312 by degrading N-acyl homoserine lactone

Abstract

Inhibiting biofilm formation triggered by a quorum sensing (QS) mechanism is promising in industries where biofilms cause deterioration of production performance. QS can be disrupted by degrading or scavenging the signal compounds that mediate QS, such as N-acyl-homoserine lactones (AHLs). This study investigated the effect of lactonase, an AHL-degrading enzyme, on bacterial biofilm formation; we applied lactonase QsdS, produced by Sphingopyxis sp. strain EG6, which was isolated from a cooling water system, to biofilms of Pseudomonas putida strain TS312, which was isolated from white water in a paper mill. Addition of QsdS lactonase inhibited biofilm formation by P. putida strain TS312; the magnitude of the effect was Qsds lactonase dose-dependent, decreasing the biofilm mass by 85% at a Qsds lactonase concentration of 10 µg/mL. Addition of QsdS lactonase decreased AHL concentrations in the culture supernatant of P. putida strain TS312, indicating that degradation of AHLs inhibited biofilm formation by disrupting QS. Observing three-dimensional biofilms by confocal laser scanning microscopy (CLSM) and optical coherence tomography (OCT) showed that addition of QsdS lactonase decreased the secretion of α-polysaccharides by P. putida strain TS312.