BIODEGRADATION OF CRUDE OIL BY FUNGI ISOLATED FROM COW DUNG CONTAMINATED SOILS

Abstract

A study was carried out to assay for oil-degrading potential of fungi isolated from cow-dung polluted soils. The samples were collected aseptically from four different cow-dung dumping sites with no history of crude-oil pollution in Akure metropolis. These samples were analyzed microbiologically using standard techniques. Sixteen fungal isolates were isolated from the polluted soils and identified. These include; Bdellospora helicoides, Aspergillus fumigatus, Gonadobotricum apiculata, Aspergillus niger, Trichoderma viridae, Pleurothecium recurvatum, Streptothrix atra, Thysarophora longispora, Candida albicans, Aspergillus flavus, Helminthosporium velutinum, Botrytis cinerea, Zoophage nitospora, Varicosporium elodeae, Articulospora inflata and Neurospora crassa were isolated from cow-dung polluted sites. The biodegradation of crude oil was observed spectrophotometrically using the broth culture of the fungal isolates for a period of 15 days on mineral salt medium. All the fungi showed degradation of the crude oil among which the isolates, Trichoderma viridae, Aspergillus flavus and Varicosporium elodeae demonstrated the best ability to degrade crude oil. Trichoderma viridae exhibited the highest degradation while Varicosporium elodeae exhibited the least degradation. The measurement of the rate of biodegradation of crude oil by the three fungi was further confirmed using Gas Chromatography and Mass Spectrophotometer (GC-MS). The GC-MS analysis showed that the fungi degraded the hydrocarbon compounds when compared to that of the control. The result obtained revealed that oil-degrading fungi can be isolated from cow-dung dumping sites and they are competent mycoflora for the biodegradation of crude oil polluted soils. They can be used as a better approach to restoring oil contaminated environments through bioremediation process.