A turbine oil-degrading bacterial consortium from soils of oil fields and its characteristics

A microbial consortium capable of degrading turbine oil (TuO), which consisted mainly of recalcitrant cycloalkanes and isoalkanes, was obtained from a soil sample collected from oil fields using repeated enrichment. When this consortium, named Atsuta A, was cultured in minimal salts medium containing 0.5% (w/v) TuO, it degraded 90% of TuO at 30 °C and pH 7 over 5 days. Although nine bacterial strains were isolated from the Atsuta A consortium, TuO degradation by the individual isolates and by a mixture of them was negligible. The community structure of the consortium, which was investigated by PCR-denaturing gradient gel electrophoresis (DGGE) targeting 16S rRNA genes, changed significantly during the degradation of TuO. Four major bands (F, K, N and T) out of at least 23 DGGE bands significantly increased in intensity over time during incubation. The DGGE bands F, K and N corresponded to those of previously isolated species. However, DGGE band T did not correspond to any isolated strain. The 16S rRNA gene sequence collected from band T was 98% homologous to that of an unculturable strain belonging to the γ-Proteobacteria. The degradation of TuO in the consortium may occur by cooperation between the unculturable species corresponding to band T and other strains in the consortium, including species corresponding to bands F, K and N.