Identification of enzyme(s) capable of degrading endosulfan and endosulfan sulfate using in silico techniques

Endosulfan is one of the most widely used organochlorine cyclodiene insecticides. Microbial oxidation of endosulfan forms endosulfan sulfate, which is more or less toxic and persistent as endosulfan. Due to lack of specificity and efficiency of microbial bioremediation technique in the field conditions, enzymatic bioremediation is receiving huge attention to clean-up the environment. In the present study, X-ray crystal structures of enzymes from Brookhaven Protein Data Bank were screened for their potential to degrade endosulfan and endosulfan sulfate using molecular docking and molecular dynamics simulation techniques. A phenol hydroxylase, 1PN0 from Trichosporon cutaneum was found to have the potential to degrade both α-endosulfan and endosulfan sulfate while a bacterial CotA laccase, 3ZDW from Bacillus subtilis has the potential to degrade α-endosulfan. The in silico result correlate with in vitro degradation study using two different strains of Trichosporon cutaneum. In vitro degradation study found that the fungal strain was capable of degrading 60.36% α-endosulfan, 70.73% β-endosulfan, and 52.08% endosulfan sulfate. The presence of phenol hydroxylase inhibitor in the sulfur-free medium with endosulfan and endosulfan sulfate as sole sulfur source inhibits the growth of both the fungal strains. Such in silico techniques can provide an easy and reliable way to speed up the development of bioremediation processes through rapid identification of potential enzymes and microbes to counter the ever-increasing number of toxic compounds in the environment.