Enhancement of the microbial degradation of crude oil by the ciliate Colpidium colpoda

Gas chromatographic analyses of Norman Wells crude oil were used to determine its biodegradability in oil-contaminated cultures containing the ciliate Colpidium colpoda and a mixture of oil-degrading bacterial species. Within these cultures the specific growth rates (b) of Colpidium ranged from 0.018 to 0.026/hr while maximum cell densities were 3,000 cells/ml. Similarly, high numbers of oil-utilizing bacteria (up to 3.86 x 108 cells/ml) were maintained throughout the experimental period. Ratios of the n-C17/pristane and n-C18/phytane p ak heights were used to assess biodegradation. Ratios in bacterized treatments without ciliates incubated for 31, 43 and 54 days were slightly lower than their respective control values. Conversely, pronounced ecreases in these ratios were apparent in cultures containing both bacteria and ciliates. Therefore, the presence of Colpidium colpoda enhanced the in vitro microbial de-gradation of crude petroleum. The importance of hydrocarbon-degrading microbial communities at oi