Submitted to: Bulletin of Environmental Contamination and Toxicology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/8/2014
Publication Date: 2/14/2014
Publication URL: http://handle.nal.usda.gov/10113/58443
Citation: Peacock, T.J., Mikell, A.T., Moore, M.T., Smith, S. 2014. Application of a redox gradostat reactor for assessing rhizosphere microorganism activity on lambda-cyhalothrin. Bulletin of Environmental Contamination and Toxicology. 92:347-351. Interpretive Summary: Bacteria have been shown to play a valuable role in degrading pesticides in the environment. However, little work has been done with bacteria present in sediment and plants commonly found in vegetated agricultural drainage ditches. Bacterial isolates, collected from plant rhizospheres in the field, were amended with the pyrethroid insecticide lambda-cyhalothrin. Specific isolates were capable of degrading the pesticide, emphasizing the importance of microbial activity in pesticide mitigation practices.
Technical Abstract: The role of bacteria in the degradation of pesticides has been investigated both at the consortial level and the isolate level. Bacterial action on a pesticide can lead to decreased toxicity potential in aquatic systems or decrease its lifetime within the environment. Increasingly there is a need for smaller more usable bioreactors that can be modified in more distinct ways to fit the environment they are attempting to mimic. Additionally the biodegradation of pesticides has traditionally used either biometers or chemostats as tools in investigating rhizosphere effects upon toxic compounds. While these devices are useful to some degree they lack some important aspects such as a solid substrate and flow through systems. In an attempt to mimic some properties of the rhizosphere of Juncus effusus, a single-stage gradostat reactor was developed. In what was developed in an attempt to study the cycling of lambda-cyhalothrin by the rhizobacteria present and the effects of Fe(III) and citrate, both common in wetland soil, upon the degradation of lambda-cyhalothrin. Through the production of a redox gradient (p<0.05), by the rhizobacteria and the ability to measure loss of lambda-cyhalothrin over time (p<0.05), the reactors were useful in expanding a system that under normal conditions would be difficult to measure.