TitleFactors influencing the proliferation of antibiotic resistance genes in the soil environment
NameSan Miguel, Cristiane (author), Tate, Robert L. (chair), Young, Lily (internal member), Gimenez, Daniel (internal member), Wawrik, Boris (outside member), Rutgers University, Graduate School - New Brunswick,
Drug resistance in microorganisms,
DescriptionManure is increasingly land applied as the organic industry booms. At the same time, antibiotic resistance (AR) in pathogenic bacteria is rendering many antibiotics useless and there is growing concern regarding AR in environmental organisms. It has been suggested that soils contain a vast and mobile reservoir of AR determinants, dubbed the soil resistome. Studies have shown the transfer of AR genes in soils, which may be enhanced by a variety of soil properties, which may, themselves, be impacted by manure amendment. Additionally, manure may contain antibiotic residues and AR enteric organisms that are introduced to soil through land application. Thus, environmental bacteria may acquire AR genes from introduced enterics or may contribute AR to these introduced species. Chapter 1 describes a study of the impact of both manure and an acidic food processing waste on a varitey of soil properties in an attempt to determine the role waste amendment may play in enhancing AR proliferation. Results indicate that manure amendment enhanced several properties associated with genetic transfer. Conversely, amendment with cranberry processing waste lowered the likelihood of AR dissemination. Analysis of metabolic diversity data revealed the limitation of Principal Component Analysis (PCA) with these datasets and a new, direct comparison analysis was developed, as outlined in Chapter 2. To investigate the possible origins of AR, a soil bacterium, isolated in 1963, was assayed for its ability to resist multiple antibiotics, including two introduced after 1963, as described in Chapter 3. It was determined that this organism was highly resistant to all drugs tested, including ciprofloxacin (CIP), a fully-synthetic compound introduced 25 years after isolation. Several resistance mechanisms, including those most common for CIP, were tested for, unsuccessfully. Thus, the mechanism(s) utilized by this organism remain unknown but appears to be novel. Chapter 4 describes a microcosm study, undertaken to evaluate the impact of manure free of antibiotics and enterics on AR proliferation. The findings indicate that “clean” manure may actually limit the occurrence of AR in the soil environment by reducing stress response in indigenous bacteria. Furthermore, the data suggest stress response can protect against therapeutic levels of antibiotic.
NoteIncludes bibliographical references
Noteby Cristiane San Miguel
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.