Introduction of atrazine-degrading Pseudomonas sp. strain ADP to enhance rhizodegradation of atrazine
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The herbicide atrazine (ATR) has been widely applied to fields in the US and Mid Western states. Recently, public health and ecological concerns have been raised about contamination of surface and ground water by the persistent ATR and its chlorinated metabolites due to their toxicity and potential carcinogenic or endocrinologic effects. Phytoremediation has been proven to be one of the most cost-effective mitigation practices for removal of ATR from surface runoff derived from agronomic operations. Current ongoing research has identified several plant species showing a promising capacity to degrade most of the soil ATR to less toxic or less mobile metabolites in the rhizosphere. However, the mineralization of ATR and its chlorinated metabolites or complete cleavage of the triazine ring in the rhizosphere was limited to less than 2-10% under both laboratory and field conditions. Despite the persistence of ATR and its degradates in the environment, a few bacteria strains including Pseudomonas sp. ADP have been isolated in the past decade from heavily contaminated ATR spill sites. These bacteria contain a series of genes encoded on the self-transmissible plasmid pADP-1 responsible for various processes of ATR degradation resulting in completed ring cleavage resulting in the rapid mineralization of ATR into carbon dioxide. We investigated the synergistic effect of introducing these biological agents to enhance the rhizodegradation of ATR. The developed knowledge may lead to future field application to reduce the local concentration of ATR and its metabolites in rhizospheres, and minimize the overall concentrations that leach into nearby water sources.