Biodegradation of phenanthrene by psychrotrophic bacteria from Lake Baikal

초록

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 15 degrees C. It could remove 26.0% of 100 mg l(-1) phenanthrene in 20 days at 15 degrees C, and degradation was less at 5 degrees C and 25 degrees C. 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 20x CMC (critical micelle concentration) of Tween 80 was added, 38.0% of 100 mg l(-1) phenanthrene was degraded in 12 days at 15 degrees C. This psychrotrophic phenanthrene-degrading bacterium is a candidate for use in bioremediation of polycyclic hydrocarbon contamination in low temperature environments.

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