ENANTIOSELECTIVE DEGRADATION OF THE HERBICIDE MECOPROP [2-(2-METHYL-4-CHLOROPHENOXY)PROPIONIC ACID] BY MIXED AND PURE BACTERIAL CULTURES

A consortium of three bacteria was isolated from top soil through thei r capacity to utilise the chlorinated, aromatic herbicide mecoprop as a single growth substrate. The consortium constituted a tight associat ion of Alcaligenes denitrificans, Pseudomonas glycinea and Pseudomonas marginalis. The culture exclusively degraded the (R)-(+)-isomer of th e herbicide while the (S)-(-)-enantiomer remained unaffected. The meco prop-degrading community could also degrade 2,4-dichlorophenoxyacetic acid, 2-methyl-4-chlorophenoxyacetic acid and racemic 2-phenoxypropion ic acid. Initially, no single member of the consortium was able to deg rade mecoprop as a pure culture but after prolonged incubation, A. den itrificans was able to grow on the herbicide as the sole source of car bon and energy.