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Sphingomonas sp. strain TTNP3 has been previously described as a bacterium that is capable of degrading the technical mixture of nonylphenol (NP) isomers and also the 4(3′,5′-dimethyl-3′-heptyl)-phenol single isomer of NP. Until recently, 3,5-dimethyl-3-heptanol was the only reported metabolite of 4(3′,5′-dimethyl-3′-heptyl)-phenol. A short time ago, the detection of an intracellular metabolite resulting from the oxidation of 4(3′,5′-dimethyl-3′-heptyl)-phenol which was identified as 2(3,5-dimethyl-3-heptyl)-benzenediol has been reported. A decisive element for this identification was the occurrence of some slight differences with the two most probable metabolites i.e. (3′,5′-dimethyl-3′-heptyl)-resorcinol and 4(3′,5′-dimethyl-3′-heptyl)-catechol. These facts led us to hypothesise some NIH shift mechanisms explaining the formation of 2(3′,5′-dimethyl-3′-heptyl)-benzenediol. In the present work, we describe the steps that led to the detection of these metabolites in the intracellular fraction of Sphingomonas sp. strain TTNP3. The formation of analogous intracellular metabolites resulting from the degradation of the technical mixture of NP is reported. To further elucidate these degradation products, studies were carried out with cells grown with 4(3′,5′-dimethyl-3′-heptyl)-phenol as sole carbon source. The description of the syntheses of reference compounds, i.e. 4(3′,5′-dimethyl-3′-heptyl)-resorcinol and 4(3′,5′-dimethyl-3′-heptyl)-catechol and their comparative analyses with the intermediates of the degradation of 4(3′,5′-dimethyl-3′-heptyl)-phenol are presented. [ABSTRACT FROM AUTHOR]

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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 α-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 α-carbon of the carbocationic intermediate formed. [ABSTRACT FROM AUTHOR]

For elucidation of the metabolism of the endocrine disruptor nonylphenol bySphingomonassp. strain TTNP3, the degradation of an isomer of nonylphenol, 4(2',6'-dimethyl-2'-heptyl)-phenol, has been studied. As in the case of 4(3',5'-dimethyl-3'-heptyl)-phenol, the metabolism of this nonylphenol isomer leads to the formation of the NIH-shifted product 2(2',6'-dimethyl-2'-heptyl)-1,4-benzenediol (NIH: National Institute of Health), but also to the alkoxy derivative 4(2',6'-dimethylheptan-2'-yloxy)phenol as additional metabolite. To the best of our knowledge, this is the first report describing the formation of alkoxyphenol as a degradation product of nonylphenol. Additionally, these results provide for the first time evidence for slight differences in the biodegradation of the isomers of nonylphenol. [ABSTRACT FROM AUTHOR]

Under alternating aerobic/anaerobic conditions and without additional carbon sources, a bacterial consortium consisting initially of 18 bacterial strains was obtained in a sequence batch reactor. The phosphorus removal capability could only be maintained using sterile filtrate of activated sludge as medium. The addition of calcium and magnesium salts, as well as vitamins and trace elements, to autoclaved sterile filtrate of activated sludge was not sufficient to achieve stable phosphorus removal. A further enrichment by subcultivation on solid agar, freezing, and shortening of the aerobic and anaerobic phases led to a defined bacterial consortium consisting of four strains. On the basis of physiological and chemotaxonomic characterization, and partial 16-S rRNA sequencing, one of the organisms was identified as Delftia acidovorans. A further isolate belonged to the Bacillus cereus group, and the third isolate was identified as Microbacterium sp.. The remaining strain seems to represent a new genus within the Flavobacteriaceae. Under continuous chemostat conditions, this consortium was able to remove up to 9.6 mg P/l phosphate in the aerobic phase and released up to 8.5 mg/l in the anaerobic phase. Up to 25 mg P-polyphosphate/g dry mass was stored under aerobic conditions. [ABSTRACT FROM AUTHOR]