1株铜绿假单胞菌对芘的降解特性及代谢途径

Degradation Characteristics and Metabolic Pathway of a Pyrene-Degrading Pseudomonas aeruginosa Strain

多环芳烃(PAHs)因其具有"三致"作用对生态系统产生潜在威胁.微生物降解是多环芳烃降解的主要途径之一,筛选出能高效降解多环芳烃的菌株是微生物修复技术的关键.本文采用富集培养的方法从多环芳烃污染的污泥中分离到1株以芘为唯一碳源的菌株LX2,经形态观察、生理生化和16S rDNA鉴定,LX2属于铜绿假单胞菌(Pseudomonas sp.LX2).菌株在含芘浓度为50 mg·L^(-1)的无机盐液体培养基中培养21 d对芘的降解效率达32.1%.经GC-MS分析发现,Pseudomonas sp.LX2降解芘的中间代谢产物主要有4,5-二氢芘、2'-羟基苯丙酮、苯酚、原儿茶酚.基于鉴定的代谢产物得出芘通过"萘"和"邻苯二甲酸"两种不同的途径被铜绿假单胞菌(Pseudomonas sp.LX2)降解.

Polycyclic aromatic hydrocarbons（ PAHs） pose a potential threat to ecosystems due to their mutagenic,carcinogenic,and teratogenic effects. Microbial degradation has been suggested as the best way to remove PAHs from contaminated environments.Screening of bacterial strains capable of efficiently degrading PAHs is the key to the bio-remediation technique. With the method of enrichment culture,the bacterial strain LX2,which can use pyrene as the sole carbon source,was isolated from sludge contaminated with PAHs. The strain was identified as Pseudomonas aeruginosa（ Pseudomonas sp. LX2） according to the results of the analyses of its morphology,physiology,and phylogeny of its 16 S rDNA sequence. The degradation rate of pyrene by Pseudomonas sp. LX2 was32. 1% after 21 days of cultivation at an initial pyrene concentration of 50 mg·L^-1. Pyrene,4,5-dihydro-,2＇-Hydroxypropiophenone,Phenol,and Protocatechuate were identified as the major metabolites by GC/MS analysis. Based on the identified metabolites,it was concluded that pyrene was degraded via two different routes by Pseudomonas aeruginosa,namely the‘naphthalene＇and the‘phthalic acid＇routes.