Kinetic analysis reveals bacterial efficacy for biodegradation of chlorpyrifos and its hydrolyzing metabolite TCP

Abstract

Efficacy of soil bacterial communities comprising seven different isolates for biodegradation of chlorpyrifos and TCP (3,5,6-trichloro-2-pyridinol), a degradation product of chlorpyrifos, has been investigated. The concentration of chlorpyrifos has ranged from 25 to 200 mg chlorpyrifos/L, and that of TCP from 25 to 100 mg TCP/L. The average values of Ks and Vmax are found to be different for isolates 1-4, 5-6 and 7 for both chlorpyrifos and TCP. The Ks has ranged from 97 to 142.3 mg/L and Vmax from 7.4 to 12.1 mg/L/d for chlorpyrifos and 103.09 to 148.8 mg/L and 14.9 to 21.2 mg/L/d, respectively, for TCP. Results indicate the high affinity of bacterial community for degradation of both chlorpyrifos and TCP. The 16S rRNA gene sequence analysis has confirmed the genetic relatedness of isolates 1-4 with Pseudomonas, isolates 5 and 6 with Agrobacterium, and isolate 7 with Bacillus. Their degradation potential for chlorpyrifos and TCP has been found to be in the order: Pseudomonas > Agrobacterium > Bacillus. It has been also observed that all seven isolates are more efficient in degrading TCP compared to chlorpyrifos. © 2011 Elsevier Ltd. All rights reserved.