School of Civil and Environmental Engineering

Ph.D. Thesis Defense Announcement

Genomic Investigations of the Role of Disinfectant-Induced Antibiotic Resistance for Public Health

By

Minjae Kim

Advisor:

Dr. Kostantinos T. Konstantinidis (CEE)

Committee Members:

Dr. Spyros Pavlostathis (CEE), Dr. Joe Brown (CEE), Dr. Frank Stewart (BIO), Dr. Karen Levy (Emory University)

Date & Time: Wednesday, May 1st, 1:00pm

Location: Ford ES&T L1116

Although most microbes are beneficial to human and animal health, there are rising public health concerns about the spread of pathogens with increasing antibiotic resistance resulting from the overuse of antibiotics and disinfectants. In this thesis, we applied traditional, culture-based laboratory techniques with cutting-edge, culture-independent omics tools to identify the molecular mechanisms responsible for disinfectant-induced antibiotic resistance in both natural and engineered settings. Our results not only helped resolving a long-standing debate on the existence (or not) of a linkage between disinfectants and antibiotics, but also identified microbial taxa and genes to biodegrade benzalkonium chlorides (BACs), a widespread class of disinfectants. These microorganisms can be employed to prevent BAC accumulation in non-target environments such as natural sediments and freshwater ecosystems. Furthermore, whole community (metagenome) sequencing was performed on DNA extracted from stool samples from young children in a low-income, urban neighborhood setting in Maputo, Mozambique, to assess the effect of shared, on-site sanitation intervention on bacterial gut infections. Our findings suggested that the intervention induces small but significant differences in abundance of several microbial species, including Veillonella parvula, an opportunistic pathogen. However, pathogen load remained high in children with intervention compared to their matched controls, indicating that alternative routes of infection remain uncontrollable.