Corvini P F X, Hollender J, Ji R, Schumacher S, Prell J, Hommes G, Priefer U, Vinken R, Schäffer A
Department of Environmental Research-Environmental Biology and Chemodynamics, RWTH Aachen, Worringerweg 1, 52074 Aachen, Germany.
Appl Microbiol Biotechnol. 2006 Mar;70(1):114-22. doi: 10.1007/s00253-005-0080-0. Epub 2005 Aug 10.
The degradation of radiolabeled 4(3',5'-dimethyl-3'-heptyl)-phenol [nonylphenol (NP)] was tested with resting cells of Sphingomonas sp. strain TTNP3. Concomitantly to the degradation of NP, a metabolite identified as hydroquinone transiently accumulated and short-chain organic acids were then produced at the expense of hydroquinone. Two other radiolabeled isomers of NP, 4(2',6'-dimethyl-2'-heptyl)-phenol and 4(3',6'-dimethyl-3'-heptyl)-phenol, were synthesized. In parallel experiments, the 4(2',6'-dimethyl-2'-heptyl)-phenol was degraded more slowly than the other isomers of NP by strain TTNP3, possibly because of effects of the side-chain structure on the kinetics of degradation. Alkylbenzenediol and alkoxyphenol derivatives identified as metabolites during previous studies were synthesized and tested as substrates. The derivatives were not degraded, which indicated that the mineralization of NP does not proceed via alkoxyphenol as the principal intermediate. The results obtained led to the elucidation of the degradation pathway of NP isomers with a quaternary alpha-carbon. The proposed mechanism is a type II ipso substitution, leading to hydroquinone and nonanol as the main metabolites and to the dead-end metabolites alkylbenzenediol or alkoxyphenol, depending on the substitution at the alpha-carbon of the carbocationic intermediate formed.
用鞘氨醇单胞菌属菌株TTNP3的静息细胞测试了放射性标记的4(3',5'-二甲基-3'-庚基)苯酚[壬基酚(NP)]的降解情况。在NP降解的同时,一种被鉴定为对苯二酚的代谢物短暂积累,随后以对苯二酚为代价产生了短链有机酸。合成了NP的另外两种放射性标记的异构体,4(2',6'-二甲基-2'-庚基)苯酚和4(3',6'-二甲基-3'-庚基)苯酚。在平行实验中,菌株TTNP3对4(2',6'-二甲基-2'-庚基)苯酚的降解速度比对NP的其他异构体慢,这可能是由于侧链结构对降解动力学的影响。合成了在先前研究中被鉴定为代谢物的烷基苯二酚和烷氧基苯酚衍生物,并将其作为底物进行测试。这些衍生物没有被降解,这表明NP的矿化不是以烷氧基苯酚作为主要中间体进行的。所获得的结果有助于阐明具有季α-碳的NP异构体的降解途径。提出的机制是II型本位取代,导致对苯二酚和壬醇作为主要代谢物,并导致终产物烷基苯二酚或烷氧基苯酚,这取决于在形成的碳正离子中间体的α-碳上的取代情况。