Physiological stress response of sediment bacteria to interacting effects of petroleum refinery effluent

Abstract

In vitro effects of the refinery effluent on physiological response of sediment bacterial strains was evaluated via reduction of 2, 3, 5-triphenyl tetrazolium chloride by dehydrogenase activity of the test organisms. Results obtained showed a range of responses by the organisms. The physiological responses of the bacterial strains were concentration-depended. Dehydrogenase activity in pure cultures of Pseudomonas sp. SD1, Bacillus sp. SD3 and Corynebacterium sp. SD4 were stimulated at effluent concentration of 12.0% (v/v), while at 25.0 %(v/v), the effluent stimulated dehydrogenase activity in Aeromonas sp. SD2. In all the cultures, dehydrogenase activity was progressively inhibited at concentrations greater than 25% (v/v). The median inhibitory concentrations of the effluent (IC₂₀) ranged from 29.076±1.05 to 42.836±2.14 and (IC₅₀) ranged from 49.905±1.16 to 58.465±2.28% (v/v) among the organisms respectively. Aeromonas sp. SD2 seemed to tolerate the toxicity of the effluent more than Pseudomonas sp.SD1 at IC₂₀ and IC₅₀. The result of the interactive effects showed that the organisms could be good candidates for bioremediation of petroleum effluents polluted media as IC₅₀ values obtained showed little high tolerance to toxic effect of petroleum refinery raw effluent by the sediment bacterial strains isolated from effluent affected Okrika River.

Keywords: Petroleum, refinery effluent, bacteria, dehydrogenase activity, bioremediation

International Journal of Natural and Applied Sciences, 7(1): 22 - 28, 2011