Anaerobic degradation and dehalogenation of chlorosalicylates and salicylate under four reducing conditions

The anaerobic biodegradability and transformation of the mono-and dichlorin ated salicylates (2-hydroxybenzoates) was examined under denitrifying, Fe ( III) reducing, sulfate reducing and methanogenic conditions. 3,6-Dichlorosa licylate and 6-chlorosalicylate are anaerobic microbial metabolites of dica mba, a widely used herbicide. Anaerobic microcosms were established with di camba treated soil from Wyoming, and golf course drainage stream sediments from New Jersey, which were each spiked with salicylate, 3,6-dichlorosalicy late or one of the four monochlorosalicylate isomers. Salicylate was degrad ed under denitrifying, sulfidogenic and methanogenic conditions. In methano genic enrichments 5-chlorosalicylate and 3-chlorosalicylate were reductivel y dehalogenated to salicylate which was then utilized. Dehalogenation of mo nochlorinated salicylates to salicylate was also observed in denitrifying c hlorosalicylate degrading cultures. The study revealed that the position of the chlorine substituent as well as the predominant electron accepting pro cess affect the rate and extent of chlorosalicylate degradation in anoxic e nvironments.