Biodegradation of imidacloprid in liquid media by an isolated soil bacteria Cytobacillus firmus strain VG5

Abstract

Imidacloprid (IMI), a neonicotinoid-class synthetic organic insecticide has the potential to have a negative influence on ecosystems and human health, and it has been identified as an emerging pollutant in all parts of the world in recent years. Microbial degradation is an efficient, clean and environmentally acceptable technique over physical and chemical methods for the bioremediation of organic contaminants like IMI. Our aim was to evaluate the ability of soil isolate Cytobacillus firmus strain VG5 to degrade IMI in MSM medium with glucose as a co-substrate. In liquid media, degradation was initially confirmed by nitrate reduction test. VG5 reduced IMI into guanidine with the removal of NO2- group and showed up to 87% degradation in 7 days. Spots with different Rf values on TLC sheet were identified by HPLC and GC-MS/ MS techniques as imidacloprid guanidine and 6-chloronicotinic acid based on respective standard spectra and m/z ratio. Strain VG5 showed potential to reduce pesticide pollution and further studies should be conducted to understand the degradation mechanism of IMI in soil under in- situ conditions.