Biodegradation of polycyclic aromatic hydrocarbons (PAHs) by novel bacterial consortia tolerant to diverse physical settings – Assessments in liquid- and slurry-phase systems

Abstract

Field-scale bioremediation of PAHs contaminated soils have proved to be difficult and challenging due to inhibited growth of PAH degrading microbes. In this study, for the first time mixed bacterial cultures designated as consortia-A and N were developed using elite metal or acid tolerant, N-fixing, P-solubilizing and biosurfactant producing PAH degraders enriched from manufactured gas plant sites. The two consortia could degrade both LMW and HMW PAHs. Kinetic studies of PAH degradation by the consortia showed the highest biodegradation rate constants (k = 0.027–0.61 day−1) and lowest half-life time (t1/2 = 1–26 days) values reported to date in liquid cultures and highlighted the use of consortium-A for the remediation of acidic soils due to its tolerance up to pH 5. Furthermore, bioaugmentation of these consortia has proven to be effective in degradation of LMW (>95%) and HMW (90%) PAHs from spiked soil slurries. Amendment of consortia-A and N exhibited 10.7 and 44.3% more total PAHs degradation, respectively than natural attenuation in 60 days even from the real long-term mixed contaminated soils. Thus the results of this study demonstrate the great potential of these novel bacterial consortia, particularly consortium-N for use in field-scale bioremediation of PAHs in long-term mixed contaminated neutral soils.