# Emerging Technologies for Degradation of Dichlorvos: A Review
## 5 Molecular Mechanism of DDVP Biodegradation  
The proposed DDVP microbial degradation pathways are presented in Figure 3. The biodegradation mechanisms of many other organophosphorus pesticides have been deeply studied, especially those pesticides whose degradation genes and enzymes were cloned and purified [67; 68; 69; 70; 71]. According to previous research, most of the microbial degradation of DDVP is closely related to a functional gene that encodes for the enzymes, which is crucial in the degradation process [64]. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**No.** & **Strain or Community** & **Sample Sources** & **Detected Metabolites** & **Comments** & **Reference** \\ \hline \multirow{7}{*}{11} & Consortium of & \multirow{4}{*}{Greenhouse within Xisanqi Ecological Garden, Beijing, China} & \multirow{4}{*}{No data respectively} & Dichlorovos degradation efficiency of these bacteria was 11.5\%,70.0\%, \\  & & & & 78.7\%, 52.6\%, 66.4\%, and 25.2\%, \\ \cline{1-1}  & & & & respectively \\ \hline \multirow{2}{*}{12} & _Pseudomonas stutzeri_ & \multirow{2}{*}{India} & \multirow{2}{*}{Free methyl and phosphate 7 th day of incubation} & \multirow{2}{*}{[65]} \\  & smk & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: _Cont._[PERSON] et al. [65] revealed the correlation between pesticide concentration and biodegradation ability. It seems that a lower concentration of DDVP supports bacterial growth, while higher concentration harms the bacteria. The reason may be that the cells and enzyme systems are hampered by increasing concentrations of pesticide, leading to lower biodegradation efficiency. [PERSON] et al. [64] also found that the enzyme produced by TaPon1-like had a low \(K_{m}\) for DDVP (0.23 mM) and a high \(K_{\text{cat}}\) (204.3 s\({}^{-1}\)). The enzyme was able to hydrolyze broad substrates with stable activity in a wide range of pH and temperature values. TaPon1-like hydrolase plays an important role in the first step of DDVP degradation by strain T23 and contributes to a comprehensive understanding of the mechanism of organophosphate pesticide degradation. The deletion of TaPon1-like weakened the efficiency of the DDVP degradation, but it did not abolish the hydrolysis ability, which indicates that TaPon1-like is one of the key enzymes of strain T23 that is responsible for the hydrolysis of the P-O bond in DDVP. Moreover, a study demonstrated that AMT-28 could produce inducible intracellular-degrading enzyme of DDVP, causing immobilized cells to display ever-increasing DDVP degradation ability in reusability determinations. To thoroughly investigate the mechanism of DDVP bioremediation, research on the isolation and purification of inducible intracellular degrading enzyme are ongoing [72]. Although the degradation mechanism has not been clearly explained, some kinds of fungi can produce novel OPs degrading enzyme [73; 74; 75]. The elimination of DDVP from saline solutions has been attributed to its ability to penetrate into the cytoplasm via a principle, called \"organic-osmolyte.\" Moreover, the PON1 gene, which exists widely in mammals, has been found to have a powerful influence on the detoxification of organophosphate compounds. This led to the result that PON1 has the ability to prevent oxidative damage to tissues, which seems to be reasonable [76]. Therefore, PON1 may prevent tissue damage due to organophosphate toxicity, especially in the central nervous system [76]. This study has shown that PON1 could effectively reduce the blood concentration and decrease the peak concentration of DDVP, and lessen the amount that enters the blood. This study also compared the hydrolytic effect of PON1 with atropine + PAM, the most widely used clinical therapy. It showed that atropine + PAM did not affect the metabolism of DDVP, which was consistent with a recent research [76].