Recent work in whole genome sequencing and bioinformatics has demonstrated the importance of horizontal gene transfer (HGT) in the development of bacterial resistance against various toxicants. These analyses have shown that many different types of mobile genetic elements (including plasmids) have been exchanged between microbial species overtime. It is generally accepted that most of the sustained adaptation events are linked to the presence of environmental selective pressures. However, it is unclear which combination of physical, chemical and biological conditions are necessary for HGT to occur. The goal of this CAREER research plan is to determine the conditions under which HGT events occur, specifically in the presence of anthropogenic contaminants. The hypothesis for this research is that beneficial genetic modification events will only occur if the recipient microorganisms have specific microbial characteristics and if the physical conditions at a given site are optimal for induction of HGT. The specific objectives of the research component of this CAREER development plan are to: 1) Identify environmental factors which control the prevalence and stability of horizontal genetic adaptation events; 2) Induce HGT in a lab scale column with a mixed microbial community and; 3) Verify if the same factors control in situ genetic adaptation for another primary substrate. Pseudomonas putida mt-2, which harbors the TOL plasmid carrying the genes for the toluene degradation pathway, will be used as the model donor bacterium. All findings will then be verified using naphthalene, another substrate which typically is degraded using plasmid encoded genes. To facilitate high throughput analysis, a fluorescent molecular detection system will be used to monitor transfer of plasmid between donor and recipient cells. These results could ultimately be transferred into the development of new genetic bioaugmentation strategies for the bioremediation of emerging contaminants which have been demonstrated to be metabolized via plasmid encoded genes. Microorganisms carrying the appropriate genes on a plasmid could be bioaugmented and, given the proper environmental conditions, these plasmids could be stimulated to transfer to native microbial species. These microorganisms would be more likely to survive under a specific site?s environmental conditions as compared to bioaugmented bacteria, thereby enabling the bioremediation of emerging contaminants at recalcitrant sites. Furthermore, beyond the bioremediation ramifications, a successful completion of these research objectives has broad relevance to other important biological research areas such as the evolution and propagation of antibiotic resistant microbes.
The main teaching and broader impact objectives of this CAREER work plan consist of the creation of an outreach program (Scientists and Engineers for the Future) aimed at introducing underrepresented minority students in middle school to science and engineering so that they may make educated career decisions. The PI and her students will develop a new outreach program entitled Scientists and Engineers for the Future aimed at introducing students in 7th and 8th grade to environmental engineering education and research. The PI will develop work plans which integrate the students curricula with innovative hands-on activities representative of the biological sciences and environmental engineering. These work plans include topics on microbiology, molecular biology and water treatment technologies. In addition, the PI will invite gifted 7th and 8th grade students to her lab and Duke microscopy facilities to demonstrate genetic adaptation events.
