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Optimizing Phytoremediation to Clean-Up Antibiotic Growth Promoters in Manure from Confined Animal Feeding Operations (CAFO)

Objective

The goal of the project is to determine the ability of phytoremediation (plant-based remediation) systems to remove antibiotic growth promoters (AGP) from manure, and to develop optimal phytoremediation processes for long-term AGP mitigation. The specific objectives that will be addressed by the proposed research include: <OL> <LI> To determine the uptake rate of AGP by selected plant catalysts. <LI>To determine the effect of physico-chemical properties on the intrinsic uptake kinetics of AGP. <LI>To develop conceptual models of single- or multi-stage phytoremediation systems for optimal AGP removal and manure treatment.

More information

NON-TECHNICAL SUMMARY: Antibiotic use as growth promoters in animal agriculture is a concern; bacterial resistance and food-borne illnesses top the list. Since feedlot effluents impair rivers and lakes significantly, AGP pose an emergent environmental hazard that needs addressing. Here, phytoremediation will be developed to remove AGP from manure. Phytoremediation uses plants to remove contaminants in engineered ecospheres, and may provide economical and lasting AGP cleanup.
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APPROACH: The ability of phytoremediation systems to remove AGP from manure will be investigated concomitant with the development of optimal bioprocesses for AGP mitigation. Phytoremediation is a mode of biological remediation of environmental pollutants that uses the capability of plants, both aquatic and terrestrial to immobilize or remove and/or transform contaminants in natural or engineered ecospheres. Here, plant-associated fates of antibiotics will be properly understood and specific plant processes will be exploited in engineered settings to achieve biofiltration or biopurification goals for AGP-contaminated animal wastes. The studies will be conducted with selected and representative AGP in two representative plant systems: (1) `natural' aquatic plants (parrot feather, water hyacinth and water lettuce) amenable for use in single- or multi-stage manure lagoons; and (2) model microbe-free root culture systems for analysis of intrinsic plant processes. Specific attention will be focused on kinetics of antibiotic uptake, affect of physico-chemical interactions of antibiotics in manure on plant uptake, and predictive models for optimal AGP phytoremediation.

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PROGRESS: 2002/07 TO 2005/06<BR>
Hairy root cultures of Helianthus annuus (sunflower) are used for studying phytoremediation of tetracycline and oxytetracycline from aqueous media. High antibiotic removal rates are obtained using hairy root cultures, as well as filtered cell-free root exudates from the hairy root cultures. Oxidation of oxytetracycline occurs by reactive oxygen species (ROS) that are produced and secreted into the aqueous environment of the plant hairy root culture. There is no evidence of modification reactions in controls, for which antibiotics are dissolved in water, under the same conditions. Addition of elicitors , such as salicylic acid and methyl jasmonate, to the plant cultures stimulate ROS secretion. The chemical mechanism of degradation of tetracyclines by ROS is studied by liquid chromatography / mass spectrometry (HPLC-MS) and fourier transform infrared (FTIR) analysis. Based on these analyses, the first reaction product appears to be converted into a hydration product, which destroys UV absorption of the molecule with ring opening and formation of a carboxylic acid. The oxidation process inactivates the oxytetracycline antibiotic activity. The same phenomenon is found using root exudates of aquatic plants, such as Myriophyllum aquaticum (parrot feather) and Pistia stratiotes (water lettuce). Impact of the research could be realized by contacting ROS from hydroponic, aeroponic or cell culture root exudates with wastewater from CAF to reduce BOD and inactivate antibiotic activities of animal growth promoters.
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IMPACT: 2002/07 TO 2005/06<BR>
The economic impact may be evaluated as costs to the CAF operator to capitalize for the process and yearly operating expenses, compared to cost of fines for being out of compliance. Enforcement is anticipated in the near future. The social and environmental impacts are respectively critical and huge, considering the potential for generation of antibiotic resistant biosystems. The scientific impact that naturally derived ROS destroy antibiotic function in wastewater is the most significant aspect of this work.

Investigators
Linden, James
Institution
Colorado State University
Start date
2002
End date
2005
Project number
COL00704
Accession number
192619