Table 4 presents removal of distillation products. Both bacteria had the ability to degrade refinery products with different boiling range. Degradation of light boiling fractions was between 80-100%. Heavy, high boiling fractions were also degraded by tested isolates. Their removal values reached between 10-80%. The reasons of poor degradability of the high boiling distillates used were their molecular size and physico-chemical parameters (especially water solubility).
Two bacteria strains isolated have special properties for petroleum hydrocarbon remediation, e.g. they produce biosurfactant and degrade petroleum hydrocarbons. Probably, the uptake and transport of hydrocarbons, and consequently the speed and degree of their degradation, were mostly improved by produced biosurfactants. However, there is no data on biosurfactant concentrations or mode of action. The beneficial effect of biosurfactants on the biodegradation process has not been evaluated.