Degradation of some phenoxy acid herbicides by mixed cultures of bacteria isolated from soil treated with 2-(2-methyl-4-chloro)phenoxypropionic acid.

Mixed bacterial cultures capable of using 2-methyl-4-chIorophenoxyacetic acid (MCPA) and 2, 4-dichlorophenoxyacetic acid (2, 4-D) as the sole source of carbon and energy were isolated from field soil treated with the herbicide (±)2-(2-methyl-4-chloro)phenoxypropionic acid (mecoprop). An enrichment technique with two aromatic compounds as sources of carbon was used. Effects of temperature and substrate concentration were studied. The mixed cultures retained their ability to degrade MCPA although the bacteria were grown for 3 months (32 successive passages) with glucose as the sole source of carbon and energy. With benzoic acid as co-substrate, one of the cultures was also able to degrade mecoprop and (±)2-(2, 4-dichloro)phenoxypropionic acid (dichlorprop). This ability was not maintained, however, over more than 10 passages.