Molecular polymorphism of chlorpyrifos-degrading strains in soil treated with controlled and non-controlled release formulations of chlorpyrifos

• We analyze the polymorphism of chlorpyrifos-degrading strains in soil.
• The residue periods of chlorpyrifos in soil under microcapsules is prolonged.
• Chlorpyrifos microcapsule can enhance the degrading ability of soil microbes to it.
• Improper use of microencapsulated pesticide may shorten its service life.

The molecular polymorphisms of chlorpyrifos (CPF)-degrading strains in soil treated with microcapsule (MC) and emulsifiable concentrate (EC) formulations of CPF were studied by laboratory experiments. Results showed that CPF residue in MC-treated soil was maintained at a certain level during 60 days, and the residual period reached 120 days. CPF residue decreased via a first-order model with a residual period of 60 days in EC-treated soil. A total of 16 and 9 degrading strains capable of utilizing CPF as a sole source of carbon and energy were isolated from these two treatments, respectively. All degrading strains were grouped into 16 different types based on enterobacterial repetitive intergenic consensus (ERIC)-PCR pattern similarities. Strains isolated from MC- and EC-treated soils belonged to 14 and 8 ERIC-types, respectively. Six groups of strains that were isolated from MC- and EC-treated soils belonged to similar ERIC-types. All ERIC-type strains were similar to nine known species according to BLAST analysis at the NCBI website. The results indicated that the population and degradation abilities of CPF-degrading strains in soil were visibly strengthened by the controlled-release formulation of CPF compared with those by the non-controlled release formulation.