Initial Stages in the Biodegradation of the Surfactant Sodium Dodecyltriethoxy Sulfate by Pseudomonas sp. Strain DES1

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Abstract
The biodegradation of the surfactant sodium dodecyltriethoxy sulfate by Pseudomonas sp. strain DES1 (isolated from activated sludge plant effluent) was studied. Growth of the organism when the 35S-labeled surfactant was present as the sole source of C and energy led to the appearance in the culture fluid of 5 35S-labeled organic metabolites. These were identified as mono-, di-, and triethylene glycol monosulfates (major metabolites) and acetic acid 2-(ethoxy sulfate) and acetic acid 2-(diethoxy sulfate), authentic samples of which were prepared and characterized. Evidently, the major metabolites were produced by rupture of 1 of the 3 ether linkages present in the surfactant molecule, probably via a single etherase enzyme. Acetic acid 2-(ethoxy sulfate) and acetic acid 2-(diethoxy sulfate) were formed by the oxidation of the free alcohol groups of di- and triethylene glycol monosulfates, respectively, and increased in amount during the stationary phase of growth. Inorganic 35S-sulfate also appeared in significant quantities in culture fluids and arose from the parent surfactant (presumably via the action of an alkylsulfatase) and not from any of the 5 metabolites. The appearance of sulfated organic metabolites during the exponential phase of growth and their quantitative relationship remained remarkably constant, even when additional C and energy sources (succinate or yeast extract) were also present in the growth media.