Degradation of Epichlorohydrin and Halohydrins by Bacterial Cultures Isolated from Freshwater Sediment

Abstract

SUMMARY: Three bacterial cultures, the Gram-negative strain AD1 andthe Gram-positive strains AD2 and AD3, were isolated from freshwatersediment after enrichment with epichlorohydrin as sole carbon source.In batch cultures of strain AD1 and strain AD3, epichlorohydrin wasrapidly degraded to 3-chloro-l,2-propanediol. Crude extracts of strainAD1 contained epoxide hydrolase activity towards epichlorohydrin,epibromohydrin, glycidol and propylene oxide as substrates. In contrast,strain AD2 did not actively convert epichlorohydrin but utilized3-chloro-l,2-propanediol produced by slow chemical hydrolysis. Noepichlorohydrin epoxide hydrolase was found in extracts of this organism.Crude extracts of strains AD1 and AD2 dehalogenated a number of mono-and dihalogenated alcohols and ketones, such as 1,3-dichloro-2-propanol,3-chloro-l,2-propanediol, l-chloro-2-propanol, l,3-dibromo-2-propanol,chloro-acetone and 1,3-dichloroacetone. Dehalogenation yielded epoxidesas products. The results suggest that epichlorohydrin is convertedby strain AD1 via 3-chloro-l,2-propanediol and glycidol by the actionof an epoxide hydrolase and a dehalogenase, respectively. The sameroute for dehalogenation proceeds in strain AD2, which, however,is dependent on chemical hydrolysis of epichlorohydrin rather thanenzymic conversion.