A Study of Ocean-Source Biosurfactant-Producing and Petroleum Hydrocarbon Degrading Bacterial Resource of The Atlantic Ocean, Araromi Sea-Side, Ondo State, Nigeria

Abstract

Bioavailability of hydrocarbons to microorganisms is a serious threat to the efficiency of biodegradation process for the decontamination of polluted environments. The objective of this research is to characterize ocean-source biosurfactant-producing bacterial resource with potential to degrade hydrocarbons. The oceanwater sample was collected from the Atlantic Ocean on latitude 6.3250338 and Longitude 4.4834361 in Ilaje Local Government Area, Ondo State, Nigeria. The Gas Chromatograph-Mass Spectrophotometry (GC-MS) analysis was used for the determination of Total Petroleum Hydrocarbons (TPHs). Quantification and identification of bacterial isolates were carried out by standard morphological, biochemical and molecular methods based on the 16S rRNA gene sequencing. Four autochthonous marine-source bacteria were evaluated for their petroleum hydrocarbon utilization potentials by spectrophotometry method at 600 nm wavelength of culture in Bushnell Haas medium fortified with 1% petroleum hydrocarbon and then assayed for biosurfactant activity by oil collapse, foaming activity, emulsification and oil drop tests. The population of hydrocarbon degrading bacteria was 9.80×104 - 3.00×105 (CFU/mL) constituting 2.09 – 6.38% of the total heterotrophic bacterial population. Lysinibacillus fusiformis (OM179766.1) Citrobacter werkmanii (CP019986.1), Lysinibacillus sphaericus (CP015224.1) and Pseudomonas putida (MT604992.1) with 94.07-99.40% percentage homology were identified from the sample and exhibited varying responses to petroleum derivatives. The isolates exhibited positive responses to biosurfactant activity except Citrobacter werkmanii which showed negative response to drop collapse test. The isolates exhibited 44-83% and 26-66% emulsification (E24) and foaming activities respectively. The results of this study conclude that there exist in the marine ecosystem diversity of biosurfactant-producing bacteria that can be exploited to enhance pollutant bioavailability for the remediation of petroleum hydrocarbon contaminated ecosystem.