Immobilized cells of a novel bacterium increased the degradation of N-methylated carbamates under low temperature conditions

Carbamates are synthetic pesticides, extensively used throughout the world due to their broad specificity against various insect pests. However, their enormous and inadequate use have made them a potential threat to the environment. At low temperature, degradation of carbamates becomes difficult mainly because of low biological activity. In the present study, we isolated a bacterial strain from a low temperature climate where the N-methylated carbamates are used for crop protection. The bacterium, was identified as Pseudomonas plecoglossicida strain (TA3) by 16S rRNA analysis. Degradation experiments with both free and immobilized cells in minimal salt medium indicated that the strain TA3 utilized carbaryl, carbofuran and aldicarb as both carbon and nitrogen source. TA3 can grow well a 4 degrees C and demonstrated the ability to degrade three carbamates (50 mu gml(-1)) at low temperature. The immobilized cells were found more efficient than their free cells counter parts. Immobilized cells has ability to degrade 100% of carbamates a 30 degrees C while 80% at 4 degrees C but incase of their free cells counter parts the efficiency to degrade carbamates was less which was 60% at 4 degrees C and 80% at 30 degrees C. TA3 free cellsextract also depicted high activity against all the three carbamates even at 4 degrees C indicating a possible enzymatic mechanism of degradation.