Isolation and Characterization of Bacteria from Refinery Effluent for Degradation of Petroleum Crude Oil in Seawater

Petroleum crude oil is transported on a global scale through marine vessels and barges by the sea route. Oil spills into the marine environment are known to cause long term effects on the health of marine life and human beings in addition to harming the eco-system. In this study, petroleum refinery effluent samples were collected and analyzed for their physico-chemical properties. Thirty two bacterial strains were isolated by direct isolation and post enrichment in crude oil. Among these, fourteen isolates could utilize petroleum hydrocarbons as sole carbon source on Bushnell Hass Agar plates supplemented with crude oil within 2 days. Out of these fourteen strains, four could decolorize 2,6-dichlorophenol indophenol within 36 h completely. They were identified as Bacillus cereus WD22, Pseudomonas aeruginosa WD23 and WDE11 (2 strains) and Acinetobacter baumannii OCB1 by 16sRNA sequencing. All four strains could tolerate salinity up to 4.0%w/v. The reduction in total petroleum hydrocarbons in sea water spiked with crude oil (1.0%v/v) supplemented with trace amounts of glucose and yeast extract was studied by gravimetric analysis. P. aeruginosa WD23 degraded 27.25% of supplied petroleum crude oil under limited nutrient conditions in seawater in 15 days. Keywords: petroleum crude oil, sea water, petroleum refinery effluent, Acinetobacter baumannii, Bacillus cereus, Pseudomonas aeruginosa