Abstract
Metabolically stable enrichment cultures of anaerobic bacteria obtained by elective enrichment of sediment samples from the Baltic Sea and Gulf of Bothnia have been used to study the oxidation and reduction of the aldehyde group of various halogenated aromatic aldehydes. During the transformation of 5- and 6-chlorovanillin, 6-bromovanillin, 3-chloro-4-hydroxybenzaldehyde, 3,5-dichloro-4-hydroxybenzaldehyde, and 3,5-dibromo-4-hydroxybenzaldehyde, it was shown that synthesis of the corresponding carboxylic acids, which were the principal metabolites, was invariably accompanied by partial reduction of the aldehyde to a hydroxymethyl group in yields of between 3 and 30%. Complete reduction to a methyl group was observed with some of the halogenated vanillins, but to an extremely limited extent with the halogenated 4-hydroxybenzaldehydes. One consortium produced both the hydroxymethyl and methyl compounds from both 5- and 6-chlorovanillin: it was therefore assumed that the methyl compound was the ultimate reduction product. On the basis of the kinetics of formation of the metabolites, it was concluded that the oxidation and reduction reactions were mechanistically related. In addition to these oxidations and reductions, dehalogenation was observed with one of the consortia. In contrast to the transformations of 5- and 6-chlorovanillin, which produced chlorinated methylcatechols, the corresponding compounds were not observed with 5- and 6-bromovanillin: the former was debrominated, forming 4-methylcatechol, whereas the latter produced 6-bromovanillyl alcohol without demethylation. Similarly, although 3-chloro-4-hydroxybenzaldehyde formed the chlorinated carboxylic acid and the benzyl alcohol, the 3-bromo compound was debrominated with formation of 4-hydroxybenzoic acid and, ultimately, phenol. On prolonged incubation, the halogenated carboxylic acids were generally decarboxylated, so that the final products from these substrates were halogenated catechols or phenols. Reductive processes of the type revealed in this study might therefore plausibly occur in the environment during anaerobic transformation of halogenated aromatic aldehydes containing hydroxyl and/or methoxyl groups.
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- Allard A. S., Remberger M., Neilson A. H. Bacterial o-methylation of chloroguaiacols: effect of substrate concentration, cell density, and growth conditions. Appl Environ Microbiol. 1985 Feb;49(2):279–288. doi: 10.1128/aem.49.2.279-288.1985. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Elsden S. R., Hilton M. G., Waller J. M. The end products of the metabolism of aromatic amino acids by Clostridia. Arch Microbiol. 1976 Apr 1;107(3):283–288. doi: 10.1007/BF00425340. [DOI] [PubMed] [Google Scholar]
- Neilson A. H., Allard A. S., Hynning P. A., Remberger M., Landner L. Bacterial methylation of chlorinated phenols and guaiacols: formation of veratroles from guaiacols and high-molecular-weight chlorinated lignin. Appl Environ Microbiol. 1983 Mar;45(3):774–783. doi: 10.1128/aem.45.3.774-783.1983. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Neilson A. H., Allard A. S., Lindgren C., Remberger M. Transformations of chloroguaiacols, chloroveratroles, and chlorocatechols by stable consortia of anaerobic bacteria. Appl Environ Microbiol. 1987 Oct;53(10):2511–2519. doi: 10.1128/aem.53.10.2511-2519.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Neilson A. H., Lindgren C., Hynning P. A., Remberger M. Methylation of halogenated phenols and thiophenols by cell extracts of gram-positive and gram-negative bacteria. Appl Environ Microbiol. 1988 Feb;54(2):524–530. doi: 10.1128/aem.54.2.524-530.1988. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pons J. L., Rimbault A., Darbord J. C., Leluan G. Biosynthèse de toluène chez Clostridium aerofoetidum souche WS. Ann Microbiol (Paris) 1984 Sep-Oct;135B(2):219–222. [PubMed] [Google Scholar]
- Yokoyama M. T., Carlson J. R. Dissimilation of tryptophan and related indolic compounds by ruminal microorganisms in vitro. Appl Microbiol. 1974 Mar;27(3):540–548. doi: 10.1128/am.27.3.540-548.1974. [DOI] [PMC free article] [PubMed] [Google Scholar]