Neonicotinoid insecticides, including thiamethoxam (THM) and imidacloprid (IMI), have become increasingly popular due to their specificity as insect neurotoxicants. However, neonicotinoids have been implicated as a potential contributing factor in Colony Collapse Disorder (CCD), the widespread disappearance of honey bees, which contribute to global produce production. The environmental persistence of neonicotinoids underscores the importance of developing a sustainable, ecologically-friendly remediation technique to remove residual THM. This study assessed the THM bioremediation potential of six bacterial species: Pseudomonas fluorescens, Pseudomonas putida, Pseudomonas aeruginosa, Alcaligenes faecalis, Escherichia coli, and Streptococcus lactis. P. fluorescens, P. putida, and P. aeruginosa were able to utilize THM over IMI as a sole carbon or nitrogen source, with better growth when THM was used as the sole nitrogen source compared to carbon. Significant (p&lt;0.0001) reductions in THM concentration in aqueous media were observed for P. fluorescens (67%), P. putida (65%), P. aeruginosa (52%), and A. faecalis (39%) over 24 days, and for E. coli (60%) and S. lactis (12%) over 14 days. The time required to remove 50% of the THM in the media was: E. coli (12d), P. fluorescens (18d), P. putida (19d), and P. aeruginosa (23d). Neither A. faecalis nor S. lactis achieved 50% removal during the study periods. Maximal thiamethoxam removal occurred at 30°C for all bacterial species assessed. HPLC chromatograms of P. fluorescens, P. putida, and E. coli cultures revealed that as the area of the THM peak decreased over time, the area of an unidentified metabolite peak increased. Identification of the metabolite is currently underway. If the metabolite is found to be less hazardous than thiamethoxam, testing will follow to evaluate this bioremediation technique in the field.

Transformation of the neonicotinoid insecticides, thiamethoxam and imidacloprid, by select bacterial species

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.