Isolation and identification of synthetic pyrethroid-degrading bacteria

Aims: To isolate, select, identify and assess the potential for the biodegradation of synthetic pyrethroids (SPs) in sheep dips. Methods and Results: SP-degrading bacteria were isolated from a mixed soil sample consisting of garden soil and soils from farms where SPs had been used. The two largest in size were then identified using microscopy, biochemical and genetic techniques to be members of the genera Pseudomonas and Serratia. By comparing the 16S rRNA gene sequences, the Pseudomonas sp. discovered was shown to group within the Pseudomonas fluorescens intrageneric cluster. The Serratia isolated was closely related to Serratia plymuthica. Cell growth and degradation was greatest in the Pseudomonas sp. culture where there was breakdown of 60 mg l(-1) to 6 mg l(-1) technical cypermethrin in 20 days. Tolerance to the SPs was greater in the Pseudomonas sp. but was found to depend on the availability of other carbon sources and nutrients. Conclusions: The bacteria characterized show the potential to be used in a bioremediation application for the treatment of SP residues. Significance and Impact of the Study: The SP-degrading bacteria may have use in the disposal of used SP residues and with further research could lead to an alternative route of disposal for use in agriculture or industry.