Establishing the Catabolic Pathway of Commercial Cypermethrin and Discovering the Inhibitor of 3- Phenoxy Benzoic Acid Biodegradation by Fig Farm Isolated Enterobacter hormaechei strain ZK101 and Stenotrophomonas maltophilia strain ZK102

Abstract

Cypermethrin (CYP) is a commonly used type Ⅱ pyrethroid against pest control in agriculture and household. Its excessive use has the potential to cause serious secondary environmental pollution. Biodegradation in the environment minimizes contamination however the metabolites, could also harm the environment more than the main product of interest. Therefore, optimum degradation rates and possible effects of bioremediation should be understood to evaluate its applicability. In this study, isolates obtained from soil exposed to CYP from fig farms in Adana were investigated to identify their CYP biodegradation pathway, and the key enzymes responsible for biodegradation, to optimize the biodegradation, and to indicate the inhibitors that affect their ability to mineralize CYP. Enterobacter hormaechei strain ZK101 and Stenotrophomonas maltophilia strain ZK102 both degraded CYP with first-order kinetics through esterification followed by 3-phenoxy benzoic acid (3PBA) deoxygenation. Strains accumulated 3PBA when they have been reinoculated to the soil due to the copper present (40 ppm) in the soil causing the inhibition of 3PBA dioxygenase. The work here is the first study that tested the potential of CYP degradation when isolates were re-inoculated in the soil and showed that CYP degraders in the field will cause an accumulation of a more toxic contaminant than CYP. The results of this study help to understand the effects of bacterial applications for CYP contamination and reveal the negative effects of microbial responses in the field.