A comparative study of the biodegradation of the surfactant sodium dodecyltriethoxy sulphate by four...

The 35S-labelled metabolites produced during biodegradation of sodium dodecyltriethoxy [35S]sulphate (SDTES) by four bacterial isolates were identified and quantified. All four isolates used ether-cleavage as the predominant primary degradation pathway. In two of the organisms, the etherase system (responsible for approx. 60-70% of primary biodegradation) liberated mono-, di- and triethylene glycol monosulphates in substantial proportions, the last two esters undergoing some further oxidation to acetic acid 2-(ethoxy sulphate) and acetic acid 2-(diethoxy sulphate), respectively. For these isolates, liberation of SO4(2-) directly from SDTES was also significant (30-40%) and the organisms were shown to contain alkyl sulphatases active towards SDTES. For the remaining two isolates, etherase action was even more important (responsible for greater than 80% of primary biodegradation) and was restricted almost totally to the alkyl-ether bond to generate mainly triethylene glycol sulphate, some of which was further oxidized. Very small amounts of diethylene glycol monosulphate were also produced, but its mono-homologue, and the oxidation products of both these esters, were absent. Small amounts of inorganic sulphate (approx. 10%) were liberated by these isolates and one of them also produced compounds tentatively identified as intermediates of omega-/beta-oxidation.