Characterization of hydrocarbon utilizing fungi from hydrocarbon polluted sediments and water

Abstract

Sediments from four different hydrocarbon polluted sites in Ogala-Bonny, Rivers State Nigeria and water samples from effluent discharge points of four different flow stations in Delta State were sampled. They were analyzed for presence of indigenous fungi. This was to establish possible fungal involvement in bioremediation of hydrocarbon polluted environments. Bushnell-Hass (mineral salt) medium supplemented with 0.05% (v/v) of streptomycin was used for the isolation and Okono medium crude oil severed as the only carbon source in the vapour phase transfer technique. The genera of fungi isolated from both samples were: Aspergillus, Candida, Penicillium, Rhizopus, Saccharomyces, Cladosporium, Fusarium and Mucor. Cladosporium, Fusarium, and Mucor were isolated only from the sediment samples. Among the genera of fungi isolated, Aspergillus had the highest frequency of occurrence 36.84% and 27.59% while Rhizopus had the least frequency of occurrence 5.26% and 3.45% for water and sediment samples respectively. Total heterotrophic count for water and sediment samples ranged from 1.9x10³ to 2.3x10⁴cfu/ml and 3.4x10⁴ to 3.8x10⁴cfu/g while hydrocarbon utilizing fungal count ranged from 1.0x10² to 3.4x10³cfu/ml and 2.6x10² to 5.7x10³cfu/g respectively. Similarly, it was observed that in both samples the total heterotrophic fungal counts were higher than hydrocarbon utilizing fungal counts which indicated chronic pollution of the sites sampled and availability of other sources of nutrient other than hydrocarbon. Species of these fungal genera isolated are known to secrete extracellular enzymes which aid in bioremediation. Under optimal environmental and nutritional conditions, the isolated fungi could be useful in the bioremediation of hydrocarbon polluted sites.

Keywords: Bioremediation; extracellular enzymes; fungi; hydrocarbon.