Abstract
The biodegradation of fatty alcohol polyglycol ethers was studied by analyzing the 14C-labeled intermediates isolated from the effluent of a model continuous-flow sewage treatment plant after dosage of either alkyl- or heptaglycol-labeled stearyl alcohol ethoxylate (SA-7EO). In each case, uncharged and carboxylated (mainly dicarboxylated) polyethylene glycols constituted the most prominent metabolites. The results indicate that there is a faster degradation of the alkyl than the polyethylene glycol moiety and that there are two distinct primary degradation mechanisms acting simultaneously in microbial biocenoses: intramolecular scission of the surfactant as well as omega- and beta-oxidation of the alkyl chain. Characterization of the bulk of 14C-labeled metabolites as a homologous series of neutral and acidic polyglycol units and identification of several C2-fragments accounted for the depolymerization of the hydrophilic part of the surfactant by stepwise cleavage of ether-bound EO units; from additional degradation studies employing either neutral or carboxylated 14C-labeled polyethylene glycols as model metabolites, it was concluded that hydrolytic as well as oxidative cleavage of C2-units is involved. Most of the identified low-molecular-weight 14C-labeled acids suggest an ultimate degradation of EO monomers by the oxidative dicarbonic acid cycle or the glycerate pathway or both. In addition, the finding of considerable amounts of oxalic and formic acids allow consideration of an additional mineralization route via glyoxylic, oxalic, and formic acids. The simultaneous action of different degradation mechanisms indicates the involvement of several distinct bacterial groups in the biodegradation of fatty alcohol ethoxylates under environmental conditions.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Child J., Willetts A. Microbial metabolism of aliphatic glycols. Bacterial metabolism of ethylene glycol. Biochim Biophys Acta. 1978 Jan 18;538(2):316–327. doi: 10.1016/0304-4165(78)90359-8. [DOI] [PubMed] [Google Scholar]
- Cox D. P. The biodegradation of polyethylene glycols. Adv Appl Microbiol. 1978;23:173–194. doi: 10.1016/s0065-2164(08)70068-6. [DOI] [PubMed] [Google Scholar]
- Gonzalez C. F., Taber W. A., Zeitoun M. A. Biodegradation of ethylene glycol by a salt-requiring bacterium. Appl Microbiol. 1972 Dec;24(6):911–919. doi: 10.1128/am.24.6.911-919.1972. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jenkins L. D., Cook K. A., Cain R. B. Microbial degradation of polyethylene glycols. J Appl Bacteriol. 1979 Aug;47(1):75–85. doi: 10.1111/j.1365-2672.1979.tb01171.x. [DOI] [PubMed] [Google Scholar]
- Kawai F., Kimura T., Fukaya M., Tani Y., Ogata K., Ueno T., Fukami H. Bacterial oxidation of polyethylene glycol. Appl Environ Microbiol. 1978 Apr;35(4):679–684. doi: 10.1128/aem.35.4.679-684.1978. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Taylor R. L., Conrad H. E. Stoichiometric depolymerization of polyuronides and glycosaminoglycuronans to monosaccharides following reduction of their carbodiimide-activated carboxyl groups. Biochemistry. 1972 Apr 11;11(8):1383–1388. doi: 10.1021/bi00758a009. [DOI] [PubMed] [Google Scholar]