EFFICIENCY OF SOME BACTERIAL CONSORTIA IN THE BIODEGRADATION OF PETROLEUM SOIL-CRUDE OIL

Abstract

Two soil textures, clay soil (CS) and sandy loam soil (SLS) were used among a simple microcosm system, and artificially spiked with 2% crude oil. The bioremediation process was continued for 60 days at 30οC for soil treated with 6 active bacterial hydrocarbon degraders. Results of the microcosm experiment showed that the total bacterial counts were higher in SLS than the CS for all treatments at different times (20, 40 and 60 days). The mixed bacterial strains (Bacillus licheniformis RdI17, Pseudomonas nitroreducens RdI14, Bacillus subtilis ssp. subtilis GH5, Sphingobacterium thalpophilum QBII6, Pseudomonas nitroreducens RdI14 and Enterobacter cloacae subsp. dissolvens) in consortium T5 was more efficient in biodegradation during the time course of experiment than other consortiaT3 and T4. Regarding the three consortia, T3, T4 and T5 results showed that the highest soil respiratory rate was 14 days post incubation during microcosm experiment and being 41.86 and 39.44 mg CO2/100 g.dw.soil for T3, 46.70 and 41.86 mg CO2/100 g.dw.soil for T4, and 49.12 and 46.70 mg CO2/100 g.dw.soil for T5 in the case of SLS and CS, respectively. Overall the GC analysis showed that the highest biodegradation of crude oil in microcosm experiment was achieved with 98.891, 79.102 and 88.724% in sandy loam soil and 93.289, 77.112 and 67.921% in CS due to bacterial consortia application.