Collaborative Research: The Role of Plants in the Environmental Fate of Growth Promoters and Antibiotics Used in Concentrated Animal Feed Operations

University Of Iowa, Iowa City IA

Investigators

Abstract

Proposal Title: Collaborative Research: The Role of Plants in the Environmental Fate of Growth Promoters and Antibiotics Used in Concentrated Animal Feed Operations Principal Investigators: Chin, Yu-Ping; Schnoor, Jerald Institutions: Ohio State University; University of Iowa Proposal No: CBET-0965863; CBET-0966683 Concentrated animal feed operation (CAFO) waste and other sources of animal manure used in land applications contain hormones (natural and administered), synthetic substances that mimic hormonal activity, and antibiotics. These substances can enter surface waters with runoff and may have deleterious effects on aquatic ecosystem such as the feminization of native fish at exceedingly low concentrations (ng/L). While microbial degradation has been documented to occur and is believed to be the primary degradation pathway, some of these substances can persist for months after the application of CAFO waste. Uptake and depuration by plants may be a cost effective means to intercept hormones, their synthetic analogs, and antibiotics in these wastes that have been applied to croplands through the use of riparian buffer strips along surface waterways. Further, evidence show that plants and sorption to soils can also prevent the introduction of these substances to groundwater. In this proposal the PIs wish to examine whether economic crop plants can transform these compounds or merely accumulate them. They will test the hypotheses that: (1) hormones (synthetic analogs and natural) and antibiotics can be taken up by plants based upon the physicochemical properties of these substances; (2) plants can both accumulate and transform these substances to benign derivatives; and (3) plant uptake and degradation complement natural attenuation in soils and in combination are an effective means to passively treat these substances. To test these hypotheses, they will examine the plant uptake and degradation of 17â-estradiol, its metabolite estrone, zeranol (a non-hormone growth promoter), and tylosin (an antibiotic) using soybean plants, a row crop plant; hybrid poplars, a tree that can be ideally used in riparian buffers; and arrow root, a native non-invasive aquatic plant. They will assess 1) sorption/desorption characteristics of the target compounds and how this process will affect their bioavailability to the plants, 2) whether transformation occurs in the plants, 3) where the compounds and their metabolites accumulate in plant tissues, and 4) the role of microbial communities in soils and the rhizosphere in the overall degradation of these compounds. Hormones, their synthetic analogs, and other pharmaceuticals released to surface waters from CAFO waste pose a threat to aquatic ecosystems. Even though natural attenuation can degrade many of these compounds, manure fertilizer can still leach these substances at levels that can harm aquatic organisms months after land application. Plant uptake and degradation complements native microbial degradation and in combination may reduce the concentration of these substances in CAFO waste to less harmful levels. The proposed work will support the graduate education of two students. The PIs are also active in disseminating this information to both the scientific community and the public at large. These include active programs involving K-12 students, the P.I.s, and their research groups. Finally, they will coordinate their efforts with their respective university extension programs to help farm communities cope with agricultural waste.