多环芳烃降解菌的筛选、鉴定及降解特性

【目的】多环芳烃(PAHs)是一类普遍存在于环境中且具有高毒性的持久性有机污染物,高效降解菌的筛选对利用生物修复技术有效去除环境中的多环芳烃具有重要意义。研究拟从供试菌株中筛选多环芳烃高效降解菌,并分析其降解特性,为多环芳烃污染环境的微生物修复提供资源保障和科学依据。【方法】采用平板法从25株供试菌株中筛选出以菲和芘为唯一碳源和能源的高效降解菌,经16S rRNA基因序列进行初步鉴定,通过单因素实验法分析其在液体培养基中的降解特性。【结果】筛选出的3株多环芳烃高效降解菌SL-1、02173和02830经16S rRNA基因序列分析,02173和02830分别与假单胞菌属中的Pseudomonas alcaliphila和Pseudomonas corrugate同源性最近,SL-1为本课题组发表新类群Rhizobium petrolearium的模式菌株;降解实验表明,菌株SL-1 3 d内对单一多环芳烃菲(100 mg/L)和芘(50 mg/L)的降解率分别达到100%和48%,5 d后能够降解74%的芘;而其3 d内对混合PAHs中菲和芘的降解率分别为75.89%和81.98%。菌株02173和02830 3 d内对混合多环芳烃中萘(200 mg/L)、芴(50 mg/L)、菲(100 mg/L)和芘(50 mg/L)的降解率均分别超过97%。【结论】筛选出的3株PAHs降解菌SL-1、02173和02830不仅可以高效降解低分子量PAHs,还对高分子量PAHs具有很好的降解潜力。研究表明,由于共代谢作用低分子量多环芳烃可促进高分子量多环芳烃的降解,而此时低分子量多环芳烃的降解将受到抑制。

Isolation, identification and degrading properties of PAHs-degrading bacteria

Objective] Polycyclic aromatic hydrocarbons (PAHs) are known as high-toxic and persistence organic contaminants in the environment. Screening highly efficient degrading bacteria is important for bioremediation of PAHs-contaminated environment. This study aimed to isolate and identify high efficient PAHs-degrading bacteria from the candidate strains, then to characterize degrading properties of these target strains. Methods] PAHs-degrading bacteria were screened by the plate-culture method, and then these target strains were identified by the 16S rRNA gene phylogenic analysis. Degrading properties of PAHs-degrading bacteria were determined by single factor experiments. Results] Three PAHs-degrading bacterial strains SL-1, 02173 and 02830, which utilized phenanthrene and pyrene as the sole carbon and energy source for growth, were obtained from the candidate strains. The strain SL-1 was the type strain of Rhizobium petrolearium. 02173 and 02830 were highly homologous to Pseudomonas alcaliphila and Pseudomonas corrugate, respectively. The strain SL-1 could degrade 100% of single phenanthrene (100 mg/L) and 48% of single pyrene (50 mg/L) in 3 days, and the degradation rate of pyrene was up to 74% in 5 days; it also could degrade 75.89% and 81.98% of mixed phenanthrene and pyrene within 3 days. The strain 02173 and 02830 could degrade a mixture of PAHs completely in 3 days, including naphthalene (200 mg/L), fluoranthene (50 mg/L), phenanthrene (100 mg/L) and pyrene (50 mg/L). Conclusion] Three PAHs-degrading bacterial strains SL-1, 02173 and 02830 have high-efficient degradation ability not only for low-molecular-weight PAHs but also high-molecular-weight PAHs. These strains were the ideal candidates for bioremediation of PAHs-contaminated environment. Low-molecular-weight PAHs can promote high-molecular-weight PAHs degradation due to con-metabolism effect, while the biodegradation of low-molecular-weight PAHs will be suppressed.