Bioremediation potential of select bacterial species for the neonicotinoid insecticides, thiamethoxam and imidacloprid.

Thiamethoxam (THM) and imidacloprid (IMI), are environmentally persistent neonicotinoid insecticides which have become increasingly favored in the past decade due to their specificity as insect neurotoxicants. However, neonicotinoids have been implicated as a potential contributing factor in Colony Collapse Disorder (CCD) which affects produce production on a global scale. The present study characterizes the bioremediation potential of six bacterial species: Pseudomonas fluorescens, Pseudomonas putida, Pseudomonas aeruginosa, Alcaligenes faecalis, Escherichia coli, and Streptococcus lactis. In Phase I, we evaluated the utilization of IMI or THM as the sole carbon or nitrogen source by P. fluorescens, P. putida, and P. aeruginosa. All three species were better able to utilize THM over IMI as their sole carbon or nitrogen source. Thus, further studies proceeded with THM only. In Phase II, we assessed the kinetics of THM removal from aqueous media by the six species. Significant (p < 0.0001) reductions in 70 mg/L THM concentration were observed for P. fluorescens (67%), P. putida (65%), P. aeruginosa (52%), and A. faecalis (39%) over the 24-day study period, and for E. coli (60%) and S. lactis (12%) over the 14-day study period. The THM removal by all species followed a first-order kinetic reaction. 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. In Phase III, we examined the effect of temperature on the transformation capacity of the bacterial species which was observed at 2 â„ƒ, 22 â„ƒ, and 30 â„ƒ. Maximal THM removal occurred at 30 °C for all bacterial species assessed. Identification of the metabolite is currently underway. If the metabolite is found to be less hazardous than THM, further testing will follow to evaluate the use of this bioremediation technique in the field.

Phytoremediation potential of switchgrass (Panicum virgatum), two United States native varieties, to remove bisphenol-A (BPA) from aqueous media.

Plastic wastes burdening Earth's water and accumulating on land, releasing toxic leachates, are one of the greatest global threats of our time. Bisphenol-A (BPA), a potent endocrine disrupting compound, is a synthetic ingredient of the polycarbonate plastics and epoxy resins used in food containers, cans, and water bottles. Bisphenol-A's rising concentrations in the environment require a sustainable alternative to current removal practices, which are expensive and/or ecologically unsafe. Switchgrass offers a safe alternative. To investigate its potential for BPA removal, two United States native switchgrass varieties where tested in hydroponic media. Results show minimal hydrolysis and photolysis of BPA over 55 days, confirming its persistence. Both generic and heavy metal switchgrass exhibited statistically significant (p < 0.0001) BPA removal (40% and 46%, respectively) over approximately 3 months, underscoring switchgrass's effectiveness for BPA removal. Significantly higher (p < 0.005) BPA accumulation in roots than shoots and nonsignificant variances in biomass, chlorophyll (p > 0.19), and peroxidase between BPA-treated and untreated plants indicates substantial BPA tolerance in both varieties. Kinetic parameters of BPA removal and translocation factors were also determined, which will inform the design of BPA removal phytotechnologies for a variety of soil conditions, including landfills where BPA accumulation is greatest.