Abstract

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This study was performed to assess the toxicity of two different domestic detergents at varying concentrations on the Aspergillus sp. subjected to different exposure times. The toxicological assessment was performed using the Aspergillus species isolated from fresh (Asarama stream, Asarama town, Andoni L.G.A) and brackish (Eagle island River, Port Harcourt) aquatic ecosystems both in Rivers state. The set-ups containing the test microorganism had the following concentrations of domestic detergents (Mymy and Zip): 6.25%, 12.5%, 25%, 50% and 75% and were exposed for 0, 4, 8, 12 and 24hrsrespectively.With the use of differential/selective media, the organism was isolated and further characterized by cell colonial and morphological identification. The median lethal concentration (Lc50) was employed to compute the toxicities of the two domestic detergents on the test organism. The result obtained showed that the Aspergillus sp. demonstrated great sensitivity to the toxicity elicited by the domestic detergents. The sensitivity of the Aspergillus sp. to the toxicity of the different toxicants, Mymy and Zip detergents from the two different water samples decreased in the following order (noting the lower the lethal concentration (Lc50), the more toxic the toxicant): Zip detergent in freshwater (37.26 mg/I) >Mymy detergent in brackish water (41.71 mg/1) > Zip detergent in brackish water (42.63 mg/1) >Mymy detergent in fresh water (47.82 mg/1). The Zip detergent showed more toxicity in fresh water with Lc50 of 37.26 and Mymy detergent showed less toxicity in fresh water with Lc50 of 47.82.

Keywords: Aspergillus species, toxicity, Mymy, zip, detergents, fresh and backish water.