萘降解细菌的分离及其降解和转座基因的分子检测

Isolation of Naphthalene-Degrading Bacteria and Molecular Detection of the Degradative and Transposable Genes

用富集培养法，从工业废水和活性污泥中分离到9个高效降解萘的细菌菌株（ND7～ND15）．对菌株ND7、ND8、ND9和ND10所进行的16SrDNA序列分析表明，它们都属于假单胞菌属（Pseudomonas）．PCR实验结果表明，上述4个菌株都含有蔡降解基因nahAc、nahG、nahH和catA，ND7和ND8菌株还含有萘降解基因nahU.DNA杂交实验结果表明，上述9个萘降解菌株都含有转座酶基因tnpA1和解体酶基因tnpR．这些结果表明，萘降解细菌的降解基因和转座基因具有高度的保守性．酶学实验证明，ND7、ND8、ND9和ND10菌株都具有儿茶酚1，2-双加氧酶活力和儿萘酚2，3-双加氧酶活力，但在不同菌株中这两种酶的比活力有明显不同．

Nine high efficient naphthalene-degrading strains （ND7- ND15） were isolated from industrial wastewater and activated sludge by enrichment culture. 16S rDNA sequencing identified the four strains among them, ND7, ND8, ND9 and ND10, as Pseudomonas. PCR experiments showed that the four strains possess naphthalene catabolic genes nahAc, nahG, nahHand catA. Moreover, strains ND7 and ND8 also contained naphthalene catabolic genes nahU. DNA hybridization experiments proved that the nine naphthalene-degrading strains have transposase gene tnpA1 and resolvase gene tnpR. These results indicated that degradative and transposable genes of the naphthalene-degrading bacteria are highly conserved. Enzymology experiments revealed that strains ND7, ND8, ND9 and ND10 could exhibit both catechol 1,2- dioxygenase and catechol 2,3-dioxygenase activities, although the specific activities of the two ezymes are different in the four strains.