Metabolism of arylsulphonates by micro-organisms

Abstract

Species of Pseudomonas capable of degrading arylsulfonates and detergents of the alkylbenzenesulfonate type were isolated from sewage and river water. Benzenesulfinate, benzenesulfonate and toluene-p-sulfonate were rapidly degraded by these organisms with the release of the sulfonate group as sulfite; detergent ho mo logues with a chain length up to 16 C atoms (4-n-hexadecylbenzenesulfonate) also released sulfite. Sulfite oxidation to sulfate in the medium can occur non-enzymically. Growth on benzenesulfonate and toluene-p-sulfonate elicited a catechol 2,3-oxygenase, which effected a ''meta'' cleavage of the ring. The metabolic route for benzenesulfonate was determined as: benzenesulfonate catechol2-hydroxymuconic semialdehyde formate and 4-hydroxy-2-oxovalerateacetaldehyde and pyruvate; the enzymes catalyzing these steps were all inducible. Toluene-p-sulfonate was degraded via 2-hydroxy-5-methylmuconic semialdehyde to formate and 4-hydroxy-2-oxohexanoate and the latter was cleaved to proplonaldehyde and pyruvate. Proplonaldehyde and propionate were oxidized rapidly by tolune-p-sulfonate-grown cells but slowly by fumarate-grown organisms. The specificity of the catechol 2,3-oxygenase induced by the arylsulfonates, towards catechol and the methylcatechols, varied during the purification suggesting that 3-methyleatechol was probably oxidized by a separate enzyme. Detergents of the alkylbenzenesulfonate type also induced a catechol 2,3-oxygenase in these bacteria. A few isolates, after growth on benzenesulfonate, opened the ring of catechol by an ''ortho''route to form cis-cis-muconate. The enzymes to degrade this intermediate to B-oxoadipate were also present in induced cells.