Characterization of alkylphenol degradation gene cluster in Pseudomonas putida MT4 and evidence of oxidation of alkylphenols and alkylcatechols with medium-length alkyl chain.

摘要: Alkylphenols (APs) are ubiquitous contaminants in aquatic environments and have endocrine disrupting toxic effects on organisms. To investigate biodegradation mechanisms of APs, an AP degradation gene cluster was cloned from a butylphenol (BP)-degrading bacterium, Pseudomonas putida MT4. The consisted 13 genes named bupBA1A2A3A4A5A6CEHIFG. From the nucleotide sequences, bupA1A2A3A4A5A6 were predicted to encode multicomponent phenol hydroxylase (PH), whereas bupBCEHIFG expected meta-cleavage pathway enzymes. A partial sequence putative NtrC-type regulatory gene, bupR, also found upstream bupB. This result indicates that APs can be initially oxidized into alkylcatechols (ACs), followed by aromatic rings. confirm this pathway, tests carried out using recombinant P. KT2440 harboring PH (bupA1A2A3A4A5A6). strain 4-n-APs with alkyl chain up C7 (< or = C7) efficiently several BPs including those some degree branching. Therefore, it had broad substrate specificity for medium-length (C3-C7). Moreover, cell extract Escherichia coli bupB (a catechol 2,3-dioxygenase gene) converted 4-n-ACs < C9 yellow products maximum absorbance at 379 nm, indicating second step enzyme is responsible ACs chain. These results suggest MT4 very useful wide range chain, which known nonylphenol-degrading Sphingomonas strains never degraded.