Anaerobic degradation of trans-cinnamate and ω-phenylalkane carboxylic acids by the photosynthetic bacterium Rhodopseudomonas palustris: evidence for a β-oxidation mechanism
- 111 Downloads
The mechanism responsible for the initial steps in the anaerobic degradation of trans-cinnamate and ω-phenylalkane carboxylates by the purple non-sulphur photosynthetic bacterium Rhodopseudomonas palustris was investigated. Phenylacetate did not support growth and there was a marked CO2 dependence for growth on acids with greater side-chain lengths. Here, CO2 was presumably acting as a redox sink for the disposal of excess reducing equivalents. Growth on benzoate did not require the addition of exogenous CO2. Aromatic acids with an odd number of side-chain carbon atoms (3-phenylpropionate, 5-phenylvalerate, 7-phenylheptanoate) gave greater apparent molar growth yields than those with an even number of side-chain carbon atoms (4-phenylbutyrate, 6-phenylhexanoate, 8-phenyloctanoate). HPLC analysis revealed that phenylacetate accumulated and persisted in the culture medium during growth on these latter compounds. Cinnamate and benzoate transiently accumulated in the culture medium during growth on 3-phenylpropionate, and benzoate alone accumulated transiently during the course of trans-cinnamate degradation. The transient accumulation of 4-phenyl-2-butenoic acid occurred during growth on 4-phenylbutyrate, and phenylacetate accumulated to a 1:1 molar stoichiometry with the initial 4-phenylbutyrate concentration. It is proposed that the initial steps in the anaerobic degradation of trans-cinnamate and the group of acids from 3-phenylpropionate to 8-phenyloctanoate involves β-oxidation of the side-chain.
Key wordsAnaerobic degradation Aromatic compounds Rhodopseudomonas palustris ω-Phenylalkane carboxylic acids trans-cinnamic acid 3-Phenylpropionic acid 4-Phenylbutyric acid β-Oxidation
Gas chromatography/Mass spectrometry
High-pressure liquid chromatography
Unable to display preview. Download preview PDF.
- Colberg PJ (1988) Anaerobic microbial degradation of cellulose, lignin, oligolignols, and monoaromatic lignin derivatives. In: Zehnder AJB (ed) Biology of anaerobic microorganisms. Wiley-Interscience, Chichester, pp 333–372Google Scholar
- Dagley S (1984) Microbial metabolism of aromatic compounds. In: Cooney CL, Humphrey AE (eds) Comprehensive Biotechnology, vol. 1. Pergamon Press, Oxford, pp 483–505Google Scholar
- Hutber GN, Ribbons DW (1983) Involvement of coenzyme A esters in the metabolism of benzoate and cyclohexanecarboxylate by Rhodopseudomonas palustris. J Gen Microbiol 129: 2413–2420Google Scholar
- Zenk MH (1978) Recent work on cinnamoyl CoA derivatives. In: Swain T, Harborne JB, VanSumere CF (eds) Recent advances in biochemistry, vol 12. Plenum Press, New York, pp 139–176Google Scholar