In the soil where most antimicrobial substance producing Microorganisms are found, life is competitive and changes in composition of microbial community due to secondary metabolites have been reported (Lancini and Perenti,1982). Thus 66.7% of the antimicrobial substances producing fungi isolated (Penicillium sp and Aspergillus sp) and the test isolates (Bacillus sp and Micrococcus sp) are efficient hydrocarbon utilizers (Amadi et al.. 1991). Based on the results obtained from this study, it shows that lots of antagonistic activity occurs amongst the hydrocarbon degraders since the inhabitants must compete for carbon, nitrogen and phosphate necessary for their growth. Successful competition may be ensured by inhibition of the growth of other organism through the production and secretion of substances interfering with their metabolism. This implies that bioremediation involving microorganisms do not occur as swiftly as assumed to be.