Petroleum Hydrocarbon Degrading Potentials Of Indigenous Bacteria Strains from “Blackwater” Ecosystem Of Eniong River – Nigeria

Abstract

Crude oil degradation by bacteria from sediments of blackwater ecosystem of Enoing River, Itu, Akwa Ibom State, Nigeria was investigated using standard microbiological and analytical protocols. Enrichment of sediment sample in mineral salt medium spiked within 2% and 1% percent crude oil resulted in Darwinian selection of 2.0 x 10³ cfu/ml and 1.4 x 10⁴ cfu/ml bacteria respectively. Crude oil utilizing rating studies revealed that isolates EHSC₁ and EHSC₂ could multiply using test oil as only source of carbon and energy as they exhibited 18mm and 17mm zone of inhibition on oil-mineral salt agar. These bacteria were further identified as Azotobacter EHSC₂ and Bacillus EHSC₁ species. Results of total viable count (TVC) revealed that Azotobacter EHSC₂ increased by a 2log magnitude (10³ to 10⁵ bacteria/ml) within 6 days while showing early decline. On the other hand, Bacillus EHSC₁ was observed to utilize crude oil more rapidly and increased by a 5log magnitude (10³ to 10⁸ cells/ml) peaking on day 9 while maintaining profuse growth till day 18. Chromatographic profiling revealed some crude oil fractions including complex carbon or long chain components (C₄, C₁₅, C₂₅, C₂₆ and C₃₀-C₃₄) showed high but varying level of degradation; these bacteria may be adapted for possible application in bioremediation strategies.