In vitro effects of petroleum refinery wastewater on dehydrogenase activity in marine bacterial strains

Toxicity of oil refinery effluent on four bacteria strains isolated from refinery effluent impacted river water sample was assessed via dehydrogenase assay. Pure cultures of the bacterial strains were exposed to various effluent concentrations [12.5 – 100% (v/v)] in a nutrient broth amended with glucose and TTC. The response of the bacterial strains to refinery effluent is concentration-dependent. At 12.5% (v/v), the effluent stimulated dehydrogenase activity in Streptococcus sp. RW3 and Pseudomonas sp. RW4. In all strains, dehydrogenase activity was progressively inhibited at concentrations greater than 12.5% (v/v). The IC50 ranges from 25.46 ± 4.75 to 31.30 ± 2.63% (v/v). The result of the in vitro study indicated that the bacterial strains are sensitive to oil refinery raw wastewater stress. Therefore, the improperly treated effluent when discharged would pose serious threat to the metabolism of the bacterial strains in natural environments.