Improved polycyclic aromatic hydrocarbon degradation in a crude oil by individual and a consortium of bacteria

In this study, we report the ability of Stenotrophomonas maltophilia, Ochrobactrum anthropi, Pseudomonas mendocina, Microbacterium esteraromaticum and Pseudomonas aeruginosa to degrade multiple polycyclic aromatic hydrocarbons (PAHs) present in crude oil. The PAHs in the crude oil sample obtained from Digboi oil refinery, India were estimated to be naphthalene (10.0 mg L-1), fluorene (1.9 mg L-1), phenanthrene (3.5 mg L-1) and benzo(b) fluoranthene (6.5 mg L-1). Exposure of individual bacteria to crude oil showed high rate of biodegradation of specific PAHs by M. esteraromaticum, 81.4%-naphthalene; P. aeruginosa, 67.1%-phenanthrene and 61.0%-benzo(b) fluoranthene; S. maltophilia, 47.9%-fluorene in 45 days. However, consortium of these bacteria showed enhanced biodegradation of 89.1%-naphthalene, 63.8%-fluorene, 81% of phenanthrene and 72.8% benzo(b) fluoranthene in the crude oil. The degradation was further improved up to 10% by consortium on addition of 40 mu g mL(-1) rhamnolipid JBR-425 biosurfactant. These results suggest that the developed bacterial consortium has significant potential in PAH remediation.