Research topics:
Microbial Cleavage of C-F bonds in Organofluorines: mechanisms, structure specificity, and integration with physiochemical approaches
Organofluorines are quite distinct from the other organohalides counterparts, in terms of physical and chemical properties. Microbial defluorination is the least understood dehalogenating process. We have observed complete decay and significant microbial reductive defluorination of specific fluorinated carboxylic acids (FCAs) in anaerobic microbial communities. However, the defluorinating microorganisms were demonstrated not to be the known dechlorinating bacteria Dehalococcoides in the community. The observed microbial defluorination is typically incomplete and not capable for more recalcitrant organofluorine structures, i.e., the legacy per- and polyfluoroalkyl substances (PFAS) like PFOA & PFOS. It is scientifically and practically crucial to obtain a mechanistic understanding of microbial defluorination to facilitate environmental monitoring, source tracking, and the development of cost-effective treatment technologies.
Current projects/aims under this topic include: (1) obtain FCA-defluorinating enrichments and isolates for physiological characterization; (2) identify the enzymes capable of catalyzing the defluorination; (3) examine the substrate specificity of the defluorinating microorganisms and defluorination pathways; (4) implement a electricity-driven microbe-material hybrid system to enhance the defluorination extent and elucidate the underlying mechanisms; (5) apply adaptive evolution to obtain more effective defluorinating microorganisms; (6) test the feasibility to combine different redox conditions and integrate with physicochemical approaches to maximize treatment efficacy. Associated Grants/Awards: - SERDP ER20-1541 - NIEHS R01 ES032668 |
Fate of antimicrobial agents and the development of antibiotic resistance in the environment
Wastewater treatment plants (WWTPs) receive a large amount of antimicrobial reagents, including antibiotics from households and hospitals. The discharge of intact or partially metabolized antimicrobial micropollutants from WWTPs into the receiving aquatic environments raise emerging concerns about the potential development of antibiotic resistant bacteria (ARB) or genes (ARG), which will impose big risks to ecosystems and the public health. The occurrence and fate of antimicrobial reagents and the presence of ARB/ARGs in natural and built environments have been widely investigated, usually in different studies. The correlation between those two in the same sampling campaign has not yet been systematically explored.
In order to help protect the environmental and human health by providing more fundamental bases, we aim to address the following research questions: 1) whether and how the presence of micropollutants in recycled water/solids affect the distribution of ARB/ARGs in the agricultural food web; 2) how non-antibiotic micropollutants would impact on the development, proliferation, and transmission of antibiotic resistance. Associated Grants/Awards: - USDA-NIFA: 2021-68015-33505 - NSF CAREER: 2045658 |