Abstract

Utilization of three petroleum hydrocarbons (Mobil SAE 40 Engine Oil, Diesel and Bonny light Crude Oil) by four bioluminescent bacteria (Vibrio harveyi, V. fisheri, Photobacterium  leiognathi and P. Phosphoreum isolated from the  Bonny estuary in the Niger Delta, Nigeria was investigated. Microbial utilization was monitored for an 8-week period using mineral salt medium containing the hydrocarbon sources as sole carbon source. Results showed that bioluminescent bacteria were widely distributed in the brackish and marine waters of the Niger Delta, representing 7.5-18.72% and 0-2-5% of the total heterotrophic bacteria of the marine and brackish water systems, respectively. A hydrocarbon loss of 100% by week 7 for all four-test organisms was observed. These results indicated that the bacteria were capable of utilizing the hydrocarbon sources as sole sources of carbon and energy. Increased phosphate concentrations (0.03-0.05 g/ml) in marine aquatic systems were also observed to stimulate increases in bacterial population and the intensity of luminescence of the bacteria. The study revealed that increasing phosphate levels in phosphate depleted marine waters would encourage the growth of hydrocarbonoclastic bioluminescent bacteria which could serve as a potential tool for the remediation of petroleum polluted marine systems of the coast of the Niger Delta. Physiochemical analyses of water from the Bonny estuary (marine) and from Isaka (brackish) environments revealed that phosphate levels in the marine system was 0.04 mg/l while in the brackish environment no phosphate was recorded (0 mg/l).

Key words: Hydrocarbonclastic, Bioluminiscent, Brackish, Marine, Remediation.