Influence of Carbon Sources on the Degradation Fenamiphos by TE1, a Rhodococcus sp

摘要

Enhanced degradation of fenamiphos (FP), resulting in reduction or loss of efficacy, has been reported. Even though degradation has been generally attributed to microorganisms, the ability of axenic cultures to degrade FP has not been reported. Futhermore, the role of organic carbon sources in the adaptation process is not clear. The Rhodococcus sp. have been shown to be efficient degraders of a number of pesticides either as sole carbon sources or in the presence of other carbon sources. Understanding the mechanisms involved in the degradation of carbamothioates and other pesticides by soil microorganisms is vital in bioremediation applications. This study was conducted to determine whether TE1, a Rhodoccocus sp isolate known to degrade various pesticides, is able to degrade FP and to determine the influence of carbon sources on the degradation of the pesticide. Isolated TE1 did not grow or use FP as sole carbon source. However, in the presence of yeast and glucose TE1 grew and degraded 11 and 10 % respectively of the parent compound in about 5 days. When the medium was supplemented with glycerol, the growth of Rhodococcus was associated with a significant degradation of FP (50%) in 5 days. The ability of TE1 to degrade FP shows that its degradation is not necessarily limited to mixed cultures as previously reported. This study also represents the first report of FP degradation by axenic cultures.