Degradation of Hydrophobic Ester Pesticides and Toxins

Abstract

The present invention relates to methods for degrading hydrophobic ester pesticides and toxins. In particular, the present invention relates to the use of insect esterases, and mutants thereof, in the bioremediation of hydrophobic ester pesticides and toxins residues, such as pyrethroid residues, contaminating the environment and horticultural commodities.

1 . A method of eliminating or reducing the concentration of a pyrethroid pesticide in a sample, the method comprising contacting the sample with an insect esterase, or a mutant thereof, wherein the esterase comprises a sequence selected from the group consisting of:
 i) the sequence set forth in SEQ ID NO:2, and   ii) a sequence which is at least 95% identical to the sequence set forth in SEQ ID NO:2 and is capable of hydrolysing a pyrethroid pesticide.   
     
     
         2 . The method of  claim 1 , wherein the mutant insect esterase is an α-carboxylesterase, and has a mutation(s) in an oxyanion hole, acyl binding pocket or anionic site regions of an active site of the esterase, or any combination thereof. 
     
     
         3 . The method of  claim 1 , wherein the mutant insect esterase is EST23W251L. 
     
     
         4 . The method of  claim 1 , wherein the method is performed using two or more insect esterases, or mutants thereof. 
     
     
         5 . The method of  claim 1 , wherein the pyrethroid is a Type I or Type II pyrethroid. 
     
     
         6 . The method of  claim 5 , wherein the Type I pyrethroid is selected from the group consisting of: 1S/1R trans permethrin, 1S/1R cis permethrin, NRDC157 1S cis, and NRDC157 1R cis. 
     
     
         7 . The method of  claim 5 , wherein the Type II pyrethroid is deltamethrin. 
     
     
         8 . The method of  claim 1 , wherein the method is performed in a liquid containing environment. 
     
     
         9 . The method of  claim 1 , wherein the insect esterase, or mutant thereof, is provided directly to the sample. 
     
     
         10 . The method of  claim 1 , wherein the insect esterase, or mutant thereof, is provided to the sample by expression of a polynucleotide encoding the insect esterase, or mutant thereof, from a host cell comprising the polynucleotide. 
     
     
         11 . The method of  claim 1 , wherein the insect esterase, or mutant thereof, is provided as a polymeric sponge or foam, the foam or sponge comprising the insect esterase, or mutant thereof, immobilized on a polymeric porous support. 
     
     
         12 . The method of  claim 1 , wherein the method further comprises the presence of a surfactant when the pyrethroid pesticide is contacted with the insect esterase, or mutant thereof. 
     
     
         13 . The method of  claim 12 , wherein the surfactant is a biosurfactant.