Swedish Environmental Research Institute, Box 21060, S-100 31 Stockholm, Sweden.
Appl Environ Microbiol. 1988 Sep;54(9):2226-36. doi: 10.1128/aem.54.9.2226-2236.1988.
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.
通过选择性富集波罗的海和波的尼亚湾沉积物样本，获得了代谢稳定的厌氧细菌富集培养物，用于研究各种卤代芳香醛的醛基的氧化和还原。在 5-和 6-氯藜芦醛、6-溴藜芦醛、3-氯-4-羟基苯甲醛、3,5-二氯-4-羟基苯甲醛和 3,5-二溴-4-羟基苯甲醛的转化过程中，表明主要代谢产物相应羧酸的合成总是伴随着醛部分还原为羟甲基，产率为 3%至 30%。一些卤代藜芦醛完全还原为甲基，但卤代 4-羟基苯甲醛的还原程度极为有限。一个共生物种可以从 5-和 6-氯藜芦醛中同时生成羟甲基和甲基化合物：因此，假设甲基化合物是最终的还原产物。基于代谢物形成的动力学，得出结论，氧化和还原反应在机制上是相关的。除了这些氧化和还原反应外，一个共生物种还观察到脱卤反应。与 5-和 6-氯藜芦醛的转化不同，后者生成氯化甲基儿茶酚，而 5-和 6-溴藜芦醛则没有观察到相应的化合物：前者脱溴，形成 4-甲基儿茶酚，而后者生成 6-溴藜芦醇而不脱甲基。同样，尽管 3-氯-4-羟基苯甲醛形成了氯化羧酸和苄醇，但 3-溴化合物脱溴形成 4-羟基苯甲酸，最终形成苯酚。在延长孵育时间后，卤代羧酸通常脱羧，因此这些底物的最终产物是卤代儿茶酚或苯酚。因此，在含有羟基和/或甲氧基的卤代芳香醛的厌氧转化过程中，本研究中揭示的还原过程可能在环境中合理发生。
