Effect of culture acclimation on the kinetics of aldicarb insecticide degradation under methanogenic conditions

This study reports on the kinetics of aldicarb transformation under methano genic conditions using batch reactors containing acclimated and unacclimate d cultures under controlled conditions. Culture acclimation was accomplishe d by exposing anaerobic microorganisms maintained in a semi-batch reactor t o low concentrations of aldicarb. Results of the kinetic studies showed tha t in an anaerobic system aldicarb is converted to aldicarb nitrile by the h ydrolytic pathway. Analysis of the hydrolysis/dehydration rate constants sh owed that anaerobic cultures enhanced the rate of conversion of aldicarb by 4-fold for acclimated cultures and by 2-fold for unacclimated cultures com pared to the rate of abiotic hydrolysis (p < 0.05). Only the acclimated cul tures were able to further mineralize the reaction intermediate aldicarb ni trile. Michaelis-Menten and Monod kinetics adequately defined the aldicarb nitrile degradation.