PCB-77 biodegradation potential of biosurfactant producing bacterial isolates recovered from contaminated soil

Abstract

Polychlorinated biphenyls (PCBs) are persistent organic pollutants widely distributed in the environment and possess deleterious health effects. The main objective of the study was to obtain bacterial isolates from PCB-contaminated soil for enhanced biodegradation of PCB-77. Selective enrichment resulted in the isolation of 33 strains of PCB-contaminated soil nearby Bhilai steel plant, Chhattisgarh, India. Based on the prominent growth using biphenyl as the sole carbon source and the confirmation of its degradation by GC-MS/MS analysis, four isolates were selected for further study. The isolates identified by 16S rRNA gene sequencing were Pseudomonas aeruginosa MAPB-2, Pseudomonas plecoglossicida MAPB-6, Brucella anthropi MAPB-9, and Priestia megaterium MAPB-27. The isolate MAPB-9 showed a degradation of 66.15% biphenyl, while MAPB-2, MAPB-6, and MAPB-27 showed a degradation of 62.06, 57.02, and 56.55%, respectively in 48 h. Additionally, the degradation ability of these strains was enhanced with addition of co-metabolite glucose (0.2%) in the culture medium. Addition of glucose showed 100% degradation of biphenyl by MAPB-9, in 48 h, while MAPB-6, MAPB-2, and MAPB-27 showed 97.1, 67.5, and 53.3% degradation, respectively as analyzed by GC-MS/MS. Furthermore, in the presence of inducer, PCB-77 was found to be 59.89, 30.49, 27.19, and 4.43% degraded by MAPB-6, MAPB-9, MAPB-2, and MAPB-27, respectively in 7 d. The production of biosurfactants that aid in biodegradation process were observed in all the isolates. This was confirmed by ATR-FTIR analysis that showed the presence of major functional groups (CH2, CH3, CH, = CH2, C–O–C, C-O) of the biosurfactant. The biosurfactants were further identified by HPTLC and GC-MS/MS analysis. Present study is the first to report PCB-77 degradation potential of Pseudomonas aeruginosa, B. anthropi, Pseudomonas plecoglossicida, and Priestia megaterium. Similarly, this is the first report on Pseudomonas plecoglossicida and Priestia megaterium for PCB biodegradation. Our results suggest that the above isolates can be used for the biodegradation of biphenyl and PCB-77 in PCB-contaminated soil.

Isolation and Characterization of Plant Growth-Promoting Bacteria for the Phytoremediation of Diesel- and Heavy Metal-Contaminated Soil

“…MAPB-27 from soil near a steel plant. Similar to the results in this study, the optimal conditions for growth were 30℃ and a pH of 7 [54]. Strain MAPB-27 also showed an emulsification capacity of 44% and degradation of 53% for chlorinated hydrocarbons [54].…”

Microbial production of cis,cis-muconic acid from aromatic compounds in engineered Pseudomonas

“…While many strains degrade biphenyl, their efficiency is poor compared to selected strains P. putida B6-2 and P. brassicacearum MPDS. For example, Brucella anthropi MAPB-9 showed 66.15% degradation of biphenyl and still required 48 h for complete mineralization of biphenyl after the addition of glucose [ 36 ]. Strain B6-2 and its mutants grew on biphenyl as the sole carbon source with 100% degradation in 12 h. Comparing wild type to mutants, the declining OD 600 value showed that knocked-out genes negatively affected strain growth.…”