Rapid Biodegradation of Phenanthrene by a Novel Strain Pseudomonas denitrificans Fdl

Aims: The aim of the study was to find, isolate, identify and characterize a phenanthrene degrader strain, and examine its ability to degrade phenanthrene.

Place and Duration of Study: Faculty of Natural Sciences, Novosibirsk State University, between September 2013 and June 2014.

Methodology: Soil was sampled from the oil contaminated area in the Purov district of the Yamal-Nenetsk Autonomous region in Russia (63.00729 NL, 76.89418 EL), and the enriched culture of oil-degraders was spread on plates with polyaromatic hydrocarbons (PAH) to isolate PAH degraders. The isolated strain was characterized morphologically, biochemically, physiologically and genetically (16S rRNA gene nucleotide sequence).

Results: By using crude oil-contaminated soil to obtain a culture enriched with oil-degraders followed by plate cultivation on phenanthrene-amended agar a bacterial strain denoted Fdl was isolated. Its cells were Gram-negative motile rods 0.4-0.5 µm wide and 1.5-2.5 µm long with phenotypic traits common for the Pseudomonas genus. The 16S rRNA gene fragment nucleotide sequence showed 99% similarity with Pseudomonas denitrificans. The isolated Pseudomonas denitrificans Fdl strain was deposited into the GenBank under access number KM 436103. Incubation of the Fdl strain cells in the medium with phenanthrene as a sole carbon source resulted in phenanthrene concentration decrease, accumulation of corresponding metabolites and bacterial proliferation, which confirmed the strain’s ability to utilize phenanthrene. Over 40 hours of incubation the phenanthrene concentration decreased from 100 to 1 ppm, proving the novel strain to be an effective phenanthrene degrader. Addition of Tween-20 non-ionic surfactant into the incubation medium accelerated phenanthrene degradation and cell proliferation as compared to phenanthrene degradation without a surfactant.

Conclusion: The isolated strain Pseudomonas denitrificans Fdl is capable of efficient phenanthrene degradation, especially in the presence of detergent, and hence can be a good candidate for biological preparations to be tested for bioremediation and sewage sludge treatment.