Antibiotic resistance genes (ARGs) make bacteria resistant to antibiotics, and disease-causing pathogens possessing ARGs can make antibiotic treatment of infectious deceases less effective in treating pathogens, and hence, threaten public health. Soil is a major environmental reservoir of ARGs, and edible crops grown in ARG-containing soils have the potential to serve as a carrier of ARGs to humans and livestock that feed on the crops. After being introduced to the soil in croplands, some ARG-carrying bacteria will reside in the surface soil, and may transfer to plant surfaces where they may be taken up by the plant. This project aims to address the knowledge gap on how ARGs are distributed in soil following the land application of fertilizer, and whether bacteria carrying ARGs survive in and on plants. This research can help determine the significance of plants as a vector for the transport of ARGs to humans. This knowledge can guide the development of management practices to prevent or minimize the uptake of ARGs to edible plants, thus protecting the Nation's food supply for the benefit of public health.<br/><br/>The goal for this project is to improve our understanding of the mechanisms that govern the fate and transport of antibiotic resistance genes (ARGs) in soil-plant ecosystems under field conditions. Three research objectives are established for the project: 1) characterize genetic resistance genes (resistome) in surface and rhizosphere soils following manure application and determine the correlation of the resistome with root exudates and antibiotics; 2) identify the source and measure the diversity of the resistome in the endophytic and epiphytic microbial communities in and on plants; 3) elucidate the metabolic adaptations that ARG-carrying bacteria use to survive in and on plants. Shotgun metagenomics will be used to study the resistome of the microbial communities in soil and plant samples, and quantitative proteomics will be used to study the protein expression of ARG-carrying bacteria living on and in plants. The research team will disseminate research findings directly to farmers and crop producers through agricultural extension education materials. The project education plan will focus on enriching student learning experiences with interdisciplinary knowledge of engineering, agriculture, and environmental science. Undergraduate students from underrepresented groups will be recruited to the project, and a new course module will be developed to show students the behaviors of ARGs in the environment.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
Antibiotic Resistance Genes in the Soil-Plant Ecosystem
Harkamal Walia, Daniel Snow; Xu Li
University of Nebraska - Lincoln