Hydrocarbon bioremediation potential of an unimpacted Kuwaiti oil-field environment

Seasonal variations in the hydrocarbon-degrading potential of soil samples from an unimpacted site in the Kuwaiti Burgan oil field environment were studied under mesophilic conditions. Hydrocarbon-degrading microorganisms occurred but varied all-year-round, and their numbers ranged from 1.3 x 10(7) to 9.3 x 10(7) CFU g(-1) dry soil, while hydrocarbon-degrading fungi ranged from 3.0 x 10(4) - 3.8 x 10(5) CFU g(-1) dry soil, depending on the sampling period. These hydrocarbon-degraders also comprised variable but generally high proportions of the total aerobic heterotrophic organisms (2 to > 98%) for bacteria and lower levels (7-9%) for fungi. The crude oil-degrading capacity of the oil-degrading populations (bacteria and fungi) ranged from 80-95% of the hexane-extractable fractions. Differential inhibition studies carried out on soil samples showed that bacteria were the greater contributors to hydrocarbon degradation (79-92%) than fungi. Pure hydrocarbon substrates, hexadecane and phenanthrene, were degraded to near completion after a 28-day incubation by both the bacterial and fungal portions of the soil flora.