N-octanoyl-DL-homoserine lactone-mediated quorum sensing enhances microbial degradation of petroleum hydrocarbons in saline-alkali soils

Abstract

Bioremediation of petroleum-contaminated soil is limited by the inherent capacity of indigenous microorganisms to metabolize petroleum hydrocarbons. Microbial proliferation could stimulate the biodegradation of pollutants. This study investigated the ability of exogenous N-octanoyl-DL-homoserine lactone (C8-HSL) to improve hydrocarbon degradation through quorum sensing (QS) regulation. Pseudomonas Stutzeri M3 was inoculated into petroleum-contaminated soil to elucidate the regulatory mechanisms of C8-HSL-mediated QS on several key factors of petroleum degradation. Specifically, it affects soil respiration activity, the activity of key degradation enzymes, and the role of extracellular polymeric substances (EPS). The findings demonstrate that adding 100 nM C8-HSL significantly increased the degradation rate of petroleum hydrocarbons in soil by 37.83 % and markedly abbreviated the overall bioremediation time. Concurrently, exogenous acyl-homoserine lactone (AHL) has been shown to augment the quantity and diversify the composition of EPS in the system. The interaction between 100 nM C8-HSL and predominant degrading bacteria (Pseudomonas) facilitates the enrichment of petroleum hydrocarbon-degrading microbial populations. This study elucidates the QS-driven mechanisms underlying efficient total petroleum hydrocarbon (TPH) degradation in soil matrices, demonstrating the pivotal role of C8-HSL in stimulating indigenous microorganisms for oilfield bioremediation. Our findings provide novel mechanistic insights into AHL-mediated QS regulation of microbial petroleum degradation. The petroleum-contaminated soil remediation technology has dual advantages in treatment efficiency and economic benefits, and it is economically and practically significant.