Isolation, identification and degradation characteristics of a phenanthrene degrading bacteria derived from seagrass sediment

Abstract:

[Background] Polycyclic aromatic hydrocarbons (PAHs) are highly toxic organic contaminants which are widely spread in the marine environment, especially in the coastal environment. As an important component of the coastal environment, seagrass ecosystems are under serious degradation status because of the effect of artificial activities including environmental pollutions. Microbial bioremediation has many advantages, such as cost-effective and environmentally friendly without secondary pollutions, and becomes the important way to restore PAHs-contaminated environments. [Objective] This study aimed to explore the feasibility of microbial remediation of PAHs-contaminants in seagrass ecosystems. Seagrass sediment from Daya Bay in Shenzhen City has been collected to isolate the effective PAHs-degrading bacterium, and the degrading characteristics of the strain have been analyzed. [Methods] The PAHs-degrading bacterium was isolated by phenanthrene as the sole carbon source, and the morphological observations, physiological and biochemical experiments and 16S rRNA gene sequences molecular analysis had been conducted for its identification. In the meanwhile, nidA gene, a functional gene for PAHs degradation, was amplified from the strain by specific primer. Finally, we used incubation experiments to analyze the strain’s degradation characteristics. [Results] A highly effective phenanthrene-degrading strain SCSIO 43702 was isolated and identified as a potentially novel species of the genus Roseovarius, and nidA gene was successfully amplified from Roseovarius SCSIO 43702. The result of incubation experiments showed that Roseovarius SCSIO 43702 could degrade 96% phenanthrene (100 mg/L) within ten days, and its optimal degrading conditions were as follows: the temperature at 30 °C, pH value at 7.5 or 8.0, salinity at 3%. [Conclusion] The bacterium Roseovarius SCSIO 43702 has high phenanthrene-degrading ability and environmental adaptability, these characteristics indicate the bacterium has great potential to be developed as microbial agents for PAHs bioremediation. All these findings in this study provide a theoretical basis and available microbial resource for bioremediation of PAHs-contaminants in the seagrass ecosystem.

Key words:polycyclic aromatic hydrocarbons (PAHs), seagrass ecosystem, PAHs-degrading bacteria, nidA gene