Assessment of Ni Toxicity to Fungi and Bacteria in Oil Tainted Soils in Greater Port Harcourt Area, Nigeria

Abstract

Intensified urbanization and industrialization are rapidly triggering the release of pollutants to the environment. This study determined the extent of soil contamination with Nickel (Ni) in oil mining areas and its effect on the levels of Ni tolerance by fungi and bacteria. The total CFUs/g of soil were enumerated after a culture period of 7 days at 28°C and LC50 was determined using probit and regression analysis. The mean values of Ni were 1.38±0.23 in industrial area, 1.41±0.36 ppm in agricultural area and 1.02±0.64 in urban area. The mean values of Total Petroleum Hydrocarbon (TPH) were 4,405.46 ppm in industrial area, 55.65 ppm in agricultural area and 1,304.53 ppm in urban area. Nickel’s peak concentration indicating growth of both fungi and bacteria at 150 ppm. There was significant difference (p ≤ 0.000) in the mean levels of LC₅₀ for fungi among the study sites. There was no significant correlation between the concentration of TPH in soil and LC₅₀ of fungi (r = -0.169) and bacteria (r = 0.042). In conclusion, TPH influenced the levels of fungi and bacteria tolerance to Ni in soils. Moreover, it was observed that LC₅₀ can be a reliable method for monitoring chemically resistant microorganisms directly in the environment to improve the use of microorganisms for the bioremediation of oil contaminated soils and in monitoring of antibiotic resistant microorganisms in natural ecosystems.