Microbial communities involved in the bioremediation of an aged recalcitrant hydrocarbon polluted soil by using organic amendments

An 8-month field bioremediation experiment using fresh (FS) and composted (CS) sewage sludge and unamended soil (US) was carried out on an aged hydrocarbon contaminated semi-arid soil. FS treatments led to the highest percentage of hydrocarbon degradation (46%) and the highest bacterial and fungal population. Denaturing gradient gel electrophoresis analysis demonstrated differences in bacterial and fungal community structure of treated compared to uncontaminated soil (control). Time of sampling accounted for most of the differences than type of treatment. The principal phyla observed in bioremediation treatments were Actinobacteria and Ascomycota. Results pointed to the addition of organic amendments, particularly sewage sludge, as an useful strategy for improving the effectiveness of landfarming biodegradation processes in hydrocarbon polluted soils.