Comparative Assessment of Crude Oil Degradation by Monocillium sp. and Aspergillus niger

Fungi dwelling in soils contaminated by petroleum products can survive on these hydrocarbons due to the highly effective extracellular enzymes. Species belonging to the genus, Aspergillus are known to be efficient degraders of various classes of hydrocarbons as well as other organic contaminants. In this study, the biodegradation of crude oil by Aspergillus niger and Monocillium sp. were compared using laboratory microcosms. The moulds were isolated from a site receiving effluent from a petroleum refinery. They were identified using their macroscopic and microscopic characteristics and subsequently screened for their ability to utilize hydrocarbons for their metabolic requirements. Following the biodegradation studies, Aspergillus niger and Monocillium sp. recorded an increase in hydrocarbon utilizing fungal counts of 8.5 x 10⁷ spores/ml and 6.1 x 10⁷ spores/ml and crude oil weight loss of 80 % and 70 %. Both fungi were tested singly and in a consortium for their ability to degrade crude oil, it was observed that Monocillium sp. and A.niger performed better when tested individually (94.2 %; 92.8 %) than in consortium (76.3 %). This may suggest that their combined metabolism may have created some antagonistic effect on the degradation process as opposed to their enzymatic capabilities which appeared to be more favourable to the process. The biodegradation experiment analysis showed that contact time plays a significant role in biodegradation of crude oil (p<0.05), and Monocillium sp. and Aspergillus niger are excellent crude oil degraders and can be used in the bioremediation of petroleum-contaminated soil and water.