Isolation, identification, and degradation characteristics of three effective PAHs degradation strains

Abstract

Isolating dominant strains for the degradation of polycyclic aromatic hydrocarbons (PAHs) is of great practical significance for the restoration of ecosystem polluted by PAHs. A total of 11 strains with capacity of degrading PAHs were obtained from soil polluted by PAHs around a coking plant, by enrichment culture, acclimation, and plate isolation. Three of them with effective PAH-degrading capability were identified and screened out by morphological observation, physiobiochemical characterization, and 16S rRNA gene sequencing, and respectively, named as DJ-3, DJ-8 and DJ-10. Based on the results of 16S rRNA gene sequencing, DJ-3, DJ-8, and DJ-10 were identified as Pseudomonas sp. Klebsiella sp., and Bacillus sp. The degradation rate of phenanthrene (200 mg·L-1), pyrene (200 mg·L-1), and naphthol (160 mg·L-1) by three strains (DJ-3, DJ-8 and DJ-10) after seven-day incubation were 48.9%-65.9%, 38.9%-43.1%, and 57.6%-64.9%, respectively. The degradation rates of mixed PAHs sample (1200 mg·L-1) by three strains were 49.1%, 44.5%, and 53.9%, which were significantly higher than other eight strains, indicating that they were highly effective in PAHs degradation. There was no antagonistic relationship among the three strains. This study would lay a foundation for building efficient PAHs degrading strains and improve the in situ bioremediation of PAHs contaminated soil.