Resuscitation-promoting factors: Novel strategies for the bioremediation of crude oil-contaminated soils

Abstract

Soil contamination with petroleum hydrocarbons is a major environmental concern. The bioremediation of these soils can be restricted because of the entry of potential microbial degraders into the viable but nonculturable (VBNC) state under unfavorable environmental conditions. Resuscitation agents can stimulate the resuscitation and growth of the bacterial population, improving their degradation capabilities. This study evaluated the efficacy of resuscitation-promoting factor (Rpf) in enhancing the biodegradation of total petroleum hydrocarbons (TPHs) in crude oil-contaminated soils, with a focus on both indigenous and augmented bacterial communities without prior resuscitation. Unlike earlier studies that focused solely on Rpf-treated populations, this study investigated the simultaneous application of Rpf and traditional biostimulation and bioaugmentation processes. Additionally, this work is the first to compare Rpf with other resuscitation agents, including supernatant Rpf (SRpf) and Micrococcus luteus. The results indicated that Rpf-supplemented biostimulation (BS + Rpf) and bioaugmentation (BAS + Rpf) processes achieved 67 and 75 degradation of 31,408 mg kg-1 TPHs within 91 days, respectively, whereas 49 and 64 degradation occured by the BS and BAS processes, respectively. Rpf stimulated the growth of bacterial populations, contributing to enhanced bioremediation of contaminated soil. Furthermore, phytotoxicity decreased with decreasing TPH concentration. These findings also demonstrated that, compared with Rpf, SRpf and M. luteus presented similar TPH removal efficiencies and seemed to be suitable alternatives to recombinant Rpf. These results provide novel insights into the activation of native bacteria by the application of resuscitation agents, demonstrating a promising approach for the bioremediation of crude oilcontaminated soils.