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Psychrotrophic phenanthrene-degrading bacteria were identified in the sediment samples collected from Lake Baikal, Russia. Among 70 phenanthrene-degrading isolates, the seven that had the highest phenanthrene-degradation rates were identified by 16S rDNA sequencing. Isolate P25, identified as the Gram-positive rod-shaped organism Rhodococcus erythropolis, had the highest growth and degradation rate at 15oC. It could remove 26.0% of 100 mg l-1 phenanthrene in 20 days at 15oC, and degradation was less at 5oC and 25oC. The addition of surfactants to enhance degradation was tested. Brij 30 and Triton X-100 inhibited degradation at all surfactant concentrations tested, but Tween 80 stimulated phenanthrene degradation, especially at low concentrations. When 20× CMC (critical micelle concentration) of Tween 80 was added, 38.0% of 100 mg l-1 phenanthrene was degraded in 12 days at 15oC. This psychrotrophic phenanthrene-degrading bacterium is a candidate for use in bioremediation of polycyclic hydrocarbon contamination in low temperature environments.
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