ω-Oxygenation of the alkyl sidechain of linear alkylbenzenesulfonate (LAS) surfactant in Parvibaculum lavamentivorans ^T

Abstract

Parvibaculum lavamentivorans ^T DS-1, an aerobic, heterotrophic bacterium, requires a biofilm on a solid surface (e.g. glass particles) when utilizing commercial linear alkylbenzenesulfonate surfactant (LAS; 20 congeners) for growth. Catabolism involves the undefined ‘ω-oxygenation’ and β-oxidation of the LAS side chain, and the organism excretes sulfophenyl carboxylates (SPC) quantitatively. A 3.5-l fermenter was developed which allowed gram-quantities of LAS-grown cells to be grown and harvested from medium with glass particles as the solid support. The catabolism of LAS was dominant: in diauxie experiments with acetate as second carbon source, LAS was utilized first. The biofilm-encoated LAS-grown cells were unsuitable for metabolic work in vitro because cell suspensions clumped and were not disrupted effectively, but the degradative enzymes were found to be expressed constitutively in acetate-grown cells, which formed no biofilm. LAS-dependent oxygen uptake was measured in acetate-grown cells at about 0.6 mkat (kg protein)⁻¹, but not in extracts of cells. Whole cells converted LAS to SPC in the presence of molecular oxygen only, and the reaction could be saturably inhibited by metyrapone, which acts on e.g. cytochromes P450 (CYP). However, despite the presence of CYP153-like sequences in the genome of strain DS-1^T, the difference spectra did not support the presence of a CYP in crude extracts, and the nature of the LAS-oxygenase remains unclear.