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Abstract: Rhodococcus erythropolis strain NTU-1 was isolated from oil-contaminated aqueous sludge and can grow at relatively high concentration of n-hexadecane as the only carbon source. The higher concentration of n-hexadecane, the faster degradation rate by NTU-1. Approximately 20,000ppmv (2%) of n-hexadecane were degraded in a treatment with 100,000ppmv (10%) within 4days of incubation. The amount of H+ ions released corresponded well to the carbon-chain length of the n-alkanes (either n-tetradecane, n-hexadecane or n-octadecane). The correspondence was 0.634mmol H+ ions accumulated per mole of n-hexadecane biodegraded. Using this correspondence, n-alkanes consumption can be closely estimated by monitoring pH changes in the medium. This procedure presents an alternative to other complex procedures that use organic solvent extractions and gas chromatography analysis. The procedure following the H+ ions accumulation was validated in a fed-batch bioreactor operation. [Copyright &y& Elsevier]

Abstract: Rhodococcus erythropolis strain NTU-1 degraded C10–C32 n-alkanes in diesel oil or crude oil. While degrading these n-alkanes, NTU-1 also trapped most other oil constitutes that were not degraded in biofloccules. In batch cultures with 10,000ppmv diesel or crude oil, approximately 90% oil removal was achieved within 4 days (about 30% of biodegradation and 60% of biosorption). In bioreactors with aeration and pH adjustment, an intermittent feed of 42,000ppmv n-hexadecane resulted in approximately 87% removal within 4 weeks (24% of biodegradation and 63% of biosorption), and an intermittent feed of 35,000ppmv diesel or crude oil resulted in more than 90% removal within 2 weeks (about 20% of biodegradation and 74% of biosorption). The results demonstrate the feasibility for the application of R. erythropolis strain NTU-1 to the bioremediation of sites polluted with petroleum spills. [ABSTRACT FROM AUTHOR]