A novel organophosphate hydrolase from Arthrobacter sp. HM01: Characterization and applications

Bioremediation systems coupled to efficient microbial enzymes have emerged as an attractive approach for the in-situ removal of hazardous organophosphates (OPs) pesticides from the polluted environment. However, the role of engineered enzymes in OPs-degradation is rarely studied. In this study, the potential OPs-hydrolase (opdH) gene (Arthrobacter sp. HM01) was isolated, cloned, expressed, and purified. The recombinant organophosphate hydrolase (ropdH) was similar to 29 kDa; which catalyzed a broad-range of OPs-pesticides in organic-solvent (similar to 99 % in 30 min), and was found to increase the catalytic efficiency by 10-folds over the native enzyme (k(cat)/K-m: 107 M- 1s(-1)). The degraded metabolites were analyzed using HPLC/GCMS. Through site-directed mutagenesis, it was confirmed that, conserved metal-bridged residue (Lys-127), plays a crucial role in OPsdegradation, which shows similar to 18-folds decline in OPs-degradation. Furthermore, the catalytic activity and its stability has been enhanced by > 2.0-fold through biochemical optimization. Thus, the study suggests that ropdH has all the required properties for OPs bioremediation.

Automated summary

This study isolated a potential organophosphate hydrolase gene and produced the recombinant enzyme through cloning, expression, and purification. The recombinant enzyme showed high catalytic efficiency for a broad range of organophosphate pesticides in organic solvents. Important catalytic residues were identified through site-directed mutagenesis. Biochemical optimization further enhanced the enzyme's catalytic activity and stability. These findings indicate the potential of this enzyme for bioremediation of organophosphate pesticides.