Minute-Speed Biodegradation of Organophosphorus Insecticides by Cupriavidus nantongensis X1^T

Abstract

Organophosphorus insecticides (OPs) have been widely used to control agricultural pests, which has raised concerns about OP residues in crops and the environment. In this study, we investigated the degradation kinetics and pathways of 8 OPs by Cupriavidus nantongensis X1T and identified the enzyme via gene cloning and in vitro assays. The degradation half-life of methyl parathion, triazophos, and phoxim was only 5, 9, and 43 min, respectively. It was 46 fold faster than that of triazophos by Bacillus sp. TAP-1, a well-studied triazophos-degrader. Strain X1T completely degraded not only chlorpyrifos, methyl parathion, parathion, fenitrothion, triazophos, and phoxim at 50 mg/L within 48 h but also the phenolic metabolites. This was the fastest degradation of OPs by bacterial whole cells reported thus far. The OPs were first hydrolyzed by an OP hydrolase encoded by the opdB gene in strain X1T, followed by further degradation of the metabolites. The crude enzyme maintained a full activity.

Enantioselective Uptake Determines Degradation Selectivity of Chiral Profenofos in Cupriavidus nantongensis X1T

“…The antibacterial activity of 2-chloro-4-bromophenol can decrease the growth of most degrading strains. However, strain X1 T can use both organophosphate and 2-chloro-4-bromophenol as the sole source of carbon and energy . Detection of two novel metabolites, depropyl-profenofos and deethylpropyl-profenofos, indicates that hydrolysis is not the only metabolic pathway of profenofos in strain X1 T .…”

“…Organophosphorus insecticides (OPs) are among the most commonly used pesticides to control agricultural and sanitary insect pests . The toxicities of OPs are mainly caused by inhibition of acetylcholinesterase in insects and mammals . Some OPs are chiral, and the insecticidal activities of chiral enantiomers vary greatly .…”

“…Phosphoric triester hydrolases (EC 3.1.8) are the main degradation enzymes of OPs, including OP acid anhydrolase (OPAA), phosphotriesterase (PTE), organophosphorus degradation enzyme (OPD), methyl parathion hydrolase (MPH), and glycerophosphodiesterase (GPD) . Although these enzymes have different protein sequences and substrate specificity, they all require divalent metal cations to catalyze substrate hydrolysis . OPD is very closely related to PTE, sharing ∼90% sequence similarity .…”

Efficient Knocking Out of the Organophosphorus Insecticides Degradation Gene opdB in Cupriavidus nantongensis X1T via CRISPR/Cas9 with Red System

“…It was previously reported that the X1 T strain is well known to have a great ability to degrade eight kinds of organophosphorus insecticides [ 40 , 41 , 46 ]. Organophosphate pesticides (OPs) can be degraded by various enzymes expressed in micro-organisms and mammals, including OP acid anhydrolase (OPAA) from rabbit tissue samples, OP-degrading hydrolases (OPHs) such as phosphotriesterase (PTE) and organophosphorus degradation enzyme (OPD), methyl parathion hydrolase (MPH) and glycerophosphodiesterase (GpdQ) from soil-dwelling microorganisms [ 47 ].…”

“…In our previous study, a novel type of strain of the genus Cupriavidus , C. nantongensis X1 T , was isolated and identified [ 39 ]. The X1 T strain could degrade eight kinds of organophosphorus insecticides (profenofos, chlorpyrifos, methyl parathion, parathion, triazophos, phoxim, fenitrothion and isocarbophos) [ 40 ]. Meanwhile, an organophosphorus degradation gene opdB , which encodes organophosphate hydrolase, was found through complete genome sequencing [ 39 , 41 ].…”