Anaerobic Desulfonation of 4-Tolylsulfonate and 2-(4-Sulfophenyl) Butyrate by a Clostridium sp.

Alkyl- and arylsulfonates were tested as sole added sources of sulfur for the growth of enrichment cultures under strictly anaerobic denitrifying or fermentative conditions. Cultures that utilized taurine, ethylsulfonate, the dyestuffs orange II and acid red I, tolylsulfonate, 2-(4-sulfophenyl)butyrate (SPB), a dialkyltetralinesulfonate, and 1-(4-sulfophenyl)octane were readily obtained. We chose to work with the simple aromatic compounds and isolated a fermentative bacterium, strain EV4, which utilized SPB as the sole added source of sulfur in glucose-mineral medium. The organism was identified as a Clostridium sp. related to Clostridium beijerinckii. Clostridium sp. strain EV4 utilized seven of seven tested arylsulfonates quantitatively. The growth yield was about 3 kg of protein per mol of sulfur, whether sulfonate or sulfate was utilized. A major product specific to each sulfonate could be observed. Although no product was identified, the existence of anaerobic desulfonation has been established.