Metabolic pathway for the biodegradation of sodium dodecyl sulfate by Pseudomonas sp. C12B

Abstract

Metabolism of sodium dodecyl sulfate (SDS) by the detergent-degrading bacterium Pseudomonas C12B has been studied using a 14C radiotracer in combination with radio-respirometry, radio-TLC, and GLC. Metabolism was extensive with 70% of the radiolabel released as 14CO2 at completion. The remainder of the radiolabel was incorporated almost totally into cells. Ether extraction of cells indicated that 14C-labeled cellular material appearing early in the uptake process was predominantly ether-extractable (mainly 1-dodecanol) and was subsequently converted to more polar metabolites. Analysis of the extractable lipids established the sequential production from [1-14C]SDS of 1-dodecanol, dodecanal, and dodecanoic acid. At this point the pathway diverged leading either to formation of 14CO2 via beta-oxidation or to elongation to C14, C16, and C18 fatty acyl residues with rapid incorporation into lipid fractions such as phospholipids. The pathway was correlated with known long-chain alkylsulfatases and alcohol dehydrogenases in this isolate and indicated that hydrophobic metabolites of the alkyl chain of surfactants can be incorporated into cellular components such as membrane lipids without prior degradation by beta-oxidation.