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.
筛选分离降解多环芳烃(PAHs)的优势菌种对开展多环芳烃污染生态系统修复具有重要的现实意义。本研究以焦化厂周围受多环芳烃污染的土壤为菌源,经过富集培养驯化和平板分离,获得11株能降解多环芳烃的菌株。通过形态观察、生理生化特征及16S rRNA序列比对对菌株进行鉴定,筛选出3株PAHs高效降解菌,分别命名为DJ-3、DJ-8、DJ-10。经16S rRNA序列分析鉴定,DJ-3为假单胞菌属、DJ-8为克雷伯氏菌属、DJ-10为芽孢杆菌属。对菌株降解能力的研究表明,3株菌(DJ-3、DJ-8、DJ-10)培养7 d后对混合多环芳烃中菲(200 mg·L-1)、芘(200 mg·L-1)和萘(160 mg·L-1)的降解率分别为48.9%～65.9%、38.9%～43.1%和57.6%～64.9%。3株菌对多环芳烃混合样品(1200 mg·L-1)的降解率分别为49.1%、44.5%、53.9%,远高于其他8株筛选菌,为PAHs高效降解菌株。3种菌株两两之间和三者组合均无拮抗关系。研究结果将为构建高效的多环芳烃降解菌群、提高多环芳烃原位污染土壤的生物修复效果奠定基础。.
Keywords: coking plant; degradation characteristics; degrading strains; isolation and identification; polycyclic aromatic hydrocarbons.