Isolation of Heterotrophic and Hydrocarbon-Utilizing Fungi from Selected Mechanic Workshops in Port Harcourt

Abstract

Spent engine oil wastes in soils are currently considered one of the most serious environmental problems. This type of pollution decreases or fully destroys soil fertility, changes the elemental composition of soil. After their introduction into soil, hydrocarbons affect soil microorganisms directly or indirectly. In this study the population of heterotrophic and hydrocarbon utilizing fungi was investigated in soils from different mechanic workshop in Port Harcourt, Rivers State. Soil physicochemical parameters such as pH, temperature, nitrate, phosphorous, potassium, total hydrocarbon content and heavy metals like Pb and Cd were also determined. Standard procedures were followed in the mycological and physicochemical parameters determination. In the soil samples, counts of the total heterotrophic fungi ranged from 0.87±3.62 to 6.9±3.37 ×104 cfu/g soil while counts of the hydrocarbon utilizing fungi ranged from 0.85 ±1.91 to 2.75±1.26 ×103 cfu/g soil. The control soil sample recorded more total heterotrophic fungal counts with significant difference while the soil from the mechanic workshops recorded more hydrocarbon utilizing fungal counts than the control soil sample and was significantly different. Eight fungal genera were isolated and they include Mucor, Aspergillus, Penicillium, Blastomyces, Scedosporium, Microsporium, Candida and Scopulariopsis. Fungal genera such as Microsporium, Candida and Scopulariopsis were not isolated from soils from the mechanic workshops but only isolated from the control soil sample. The pH values ranged between 5.81 to 7.91, temperature ranged from 27.7 to 30 oC, nitrate value ranged from 0.04 to 0.21 mg/kg, PO4 ranged from 1.10 to 3.42 mg/kg, total hydrocarbon content (THC) value ranged from 0 to 170.01 mg/kg, potassium (K) value ranged from 5.063 to 17.013 mg/kg. The heavy metals analyzed were Pb (Lead) and Cd (Cadmium). The Pb ranged from 0.10 to 5.12463 mg/kg, cadmium ranged from 0.13 to 1.65072 mg/kg. The soil samples from mechanic workshops were contaminated with hydrocarbons, and the fungal isolates were primarily hydrocarbon utilizers that may be exploited for contaminated soil bioremediation.