The toxicological bioassay of petroleum products (industrial and local ‘kpo-fire’ refined Kerosene) in tri-aquatic ecosystem (marine, brackish and freshwater) using pollution bio-monitor Pseudomonas sp. were investigated. The study employs experimental examination and statistical analysis of data and interpretation. It was designed to evaluate the different kerosene concentration and the duration of exposure that could cause potential toxicological effect on Pseudomonas sp. in tri-aquatic ecosystem which was used as indices to access level of pollution. Standard microbiological techniques were used; toxicity procedure were applied using local and industrial refined kerosene; prepared at concentrations of 1.625%, 3.25%, 6.5%, 12.5% and 25% in fresh, brackish and marine water; total of 36 different microcosms. These were tested with Pseudomonas sp. for 0, 4, 8, 12 and 24 h separately for each toxicant. The cultures were incubated at 35°C for 24 hours. The median lethal concentration (LC50) was employed to compute the toxicities of the different toxicants on the test organism. The results specify that percentage (%) logarithm of mortality of Pseudomonas sp. increases with increased toxicants concentration and exposure time. The pollution bio-monitor Pseudomonas sp. demonstrated sensitivity to the toxicity of local and industrially refined kerosene. The sensitivity showed variations, toxic level decreased in the following order (noting that the lower the LC50, the more toxic the toxicants): Industrial refined kerosene in fresh water (18.79%) > Industrial refined kerosene in brackish water (20.81%) > Local refined kerosene in brackish water (21.47%) > Industrial refined kerosene in marine water (22.66%) > Local refined kerosene > (24.25) > Local refined kerosene in marine water (24.94%). Using the Pollution/Toxicity Bio-monitoring evaluation Chart; Local refined kerosene in marine, brackish and freshwater were ‘Toxic [High], Industrial refined kerosene in marine water was ‘Toxic [High]’ while Industrial refined kerosene in brackish and freshwater were ‘Toxic [very High]’. Conclusion: The study showed that industrial refined kerosene in fresh water (LC50 = 18.8%) has the highest toxicity strength while local refined kerosene in marine water (LC50 = 24.92%) has the least toxicity strength on Pseudomonas sp. in the tri-aquatic ecosystem. These results show that local and industrial refined kerosene can inhibit the growth of Pseudomonas sp. in an aquatic ecosystem; noting that Pseudomonas sp. is one of the most effective biodegrading bacteria in ecological biogeochemical cycles, pollutant removal/remediation and a key pollution bio-monitoring. Pseudomonas sp. tolerance for hydrocarbon and its initial sensitivity per mortality within 24 hours of exposure could be accessed as indices to measure level of pollution or toxicity of petroleum products.
Dr. Renner Renner Nrior
Department of Microbiology, Faculty of Science, Rivers State University, Port Harcourt, Nigeria.
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