ISOLATION AND CHARACTERIZATION OF ALKALI-TOLERANT CRUDE OIL DEGRADING BACTERIA CONSORTIA FROM THE OILY SLUDGE

This study details the indigenous oil-degrading consortia, using crude oil as sole carbon and energy sources, which were screened out from the oily sludge of Central-Asia arid region via a crude oil mineral salt medium (MSM) plate tests. The enriched consortia are considered as heterotrophic alkali-tolerant microorganisms, which readily grew under the pH 6.0-12.0. Moreover, petroleum hydrocarbon degradation in water exhibited that the decomposition rate was the highest at pH 11.0 and reached 68.57% for the 8 d period. For the alkaline oily sludge with pH of similar to 10, the selected consortia could consume 60% of petroleum hydrocarbon in 7 days of aerobic cultivation, indicating that it had the potential practical application in remediation of crude oil-contaminated saline-alkaline soil and sludge. GC-MS analysis of the residual hydrocarbons showed that chain saturated alkane (C8 to C20) was greater than 90% treated for 8 days. Based on 16S rRNA gene sequences, the consortia were identified as Porphyrobactercryptus, Staphylococcus epidermidis, and Pseudomonas aeruginosa. Overall, the obtained oil-degrading strain presented a short growth period, the ease of isolation and screening, as well as the high crude oil degradation capacity and alkali-tolerant property, which would endow it to degrade crude-oil under alkali-wastewater or sludge.