Natural transformation and growth inhibition of azotobacter vinelandii in the presence of adsorbed oxytetracycline

Antimicrobial resistance genes and antimicrobials are introduced to agricultural soil through land application of manure. Both can persist in the environment if adsorbed to soil grains, allowing potential for increased antimicrobial resistance in the soil microbial community. Oxytetracycline (OTC) is a commonly used antimicrobial in large-scale livestock production systems that can persist in the environment. To better understand how adsorbed antimicrobials could affect antimicrobial resistance, the mechanism of OTC adsorption to a clay soil was investigated using sorption isotherm experiments and modeling, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Sorption data showed a good fit with a cation-exchange capacity sorption model. FTIR results revealed oxytetracycline sorption to this clay soil by electrostatic interactions between the protonated dimethylamino group of oxytetracycline and the negative charge on the surface of the soil. XRD results revealed that OTC adsorbed to the surface of non-expandable illites and significantly influenced how water molecules interact with expandable clay minerals. In addition, the influence of oxytetracycline adsorbed to sterile soil on the natural transformation and inhibition of the soil bacterium Azotobacter vinelandii was investigated. The transformation frequency by both plasmid and chromosomal DNA was not significantly affected by the addition of adsorbed OTC, showing that the presence of OTC does not hinder gene transfer. A higher concentration of adsorbed OTC compared to dissolved OTC was required to inhibit growth, which may select bacteria in the soil community.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Environ Engr in Civil Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Goetsch, Heather E.

Contributors dc:contributor

• Zilles, Julie L.
• Nguyen, Helen

• Oxytetracycline
• Natural Transformation
• Adsorption
• Antimicrobial Resistance

Statement dc:rights

• Copyright 2011 Heather E. Goetsch

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/24414

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/24414