Phenanthrene degradation by Pseudoxanthomonas sp. DMVP2 isolated from hydrocarbon contaminated sediment of Amlakhadi canal, Gujarat, India.

Amlakhadi canal, flowing through Ankleshwar (Gujarat, India) has been impinged with various xenobiotic compounds, released in industrial discharges, over last many decades. Twenty five bacterial strains capable of phenanthrene degradation were isolated from sediments of Amlakhadi canal. The best strain amongst them was identified as Pseudoxanthomonas sp. DMVP2 based on 16S rRNA gene sequence analysis, and selected for further studies. Experiments were carried out for optimization of abiotic parameters for efficient phenanthrene degradation. Strain DMVP2 was able to degrade 300 ppm of phenanthrene completely in minimal medium containing peptone (0.1%, w/v) as nitrogen source with initial pH 8.0 at 37°C under shaking condition (150 rpm) within 120 h. Strain DMVP2 was able to consume 1,600 mg/l of phenanthrene even at high initial concentration (4,000 mg/l) of phenanthrene. Identification of phthalic acid as major metabolite on GC-MS analysis and detection of protocatechuate dioxygenase activity revealed that phenanthrene was metabolized by phthalic acid-protocatechuate acid pathway. Strain DMVP2 was also able to utilize other xenobiotic compounds as sole carbon source and degrade phenanthrene in presence of other petroleum hydrocarbons. Consequently, Pseudoxanthomonas sp. DMVP2 has potential applications in bioremediation strategies.