Isolation and characterization of engine oil degrading indigenous microrganisms in Kwazulu-Natal, South Africa

As the usage of petroleum hydrocarbon products increases, soil contamination with diesel and engine oils is becoming one of the major environmental problems. To investigate the countermeasure to remediate soils contaminated with oils, bioremediation provide an effective and efficient strategy to speed up the clean-up processes. Three bacterial isolates capable of utilizing used engine-oil as a carbon source were isolated from contaminated soils using the enrichment technique. Three isolates were identified as Flavobacterium sp., Acinetobacterium calcoaceticum and Pseudomonas aeruginosa based on biochemical tests and 16S rRNA sequencing. The gavimetric analysis revealed that A. calcoaceticum and a consortium of the isolates were capable of utilizing 80 and 90% of used engine oil, respectively, under laboratory conditions at 30°C and 160 rpm with Bushnell-Haas media in a 4 week period. An increase in oil degradation is correlated to an increase in cell number indicating that the bacterial isolates were responsible for the oil degradation. All isolates were capable of degrading the nparaffin up to 80% in a 2 week period. The optimal temperatures at which biodegradation occurred at 30–37°C. The preference of nitrogen sources and minimal salts were different for different bacterial isolates. The results obtained demonstrate the potential for oil bioremediation of these isolates in situ and/or ex situ.