Identification of Rhodococcus erythropolis isolates capable of degrading the fungicide carbendazim

Continuous enrichment cultures were used to identify bacterial isolates capable of degrading the fungicide carbendazim. The bacteria originated from sites that had been repeatedly treated with the structurally related parent fungicide, benomyl, over a period of several years. Six isolates were identified as carbendazim degraders on the basis of their ability to produce diffusion-clearing zones on a minimal salts solid medium spray-coated with a 0.1% solution of carbendazim, their ability to grow in a minimal salts broth supplemented with carbendazim as the sole carbon source, and their ability to reduce carbendazim levels in liquid cultures. All six isolates were identified as Rhodococcus erythropolis or a closely related species by analyses of nutritional utilization and whole-cell fatty acid methyl ester profiles. A chemically induced mutant of R. erythropolis isolate B2E was identified that wits no longer capable of degrading carbendazim, as determined by negative results in all three assays. Further characterization of these strains provides an opportunity for their development in bioremediation of the compound.