Subproject: REU Supplement for CAREER: Redefining 'antimicrobial' in the context of microbe-chemical interactions indoors

Although humans spend upwards of 90% of their time indoors, very little is understood about the myriad chemical and biological exposures that take place inside of buildings, with serious potential implications for human health. This CAREER proposal describes a multipronged approach to leverage molecular microbiology and analytical chemistry to arrive at a fundamental understanding of how chemicals and the indoor microbiome interact. This is potentially transformative because if successful it will fundamentally change the way we design and maintain interior environments. Moreover, it will radically change the way people think about antimicrobial products and microbes indoors. Specifically, the proposed work examines antimicrobial (AM) chemicals in textiles and their effects on undomesticated indoor microbial communities. The focus of this project is AMs because they are widely used but their impacts on microbes in situ are largely uncharacterized and may include adverse effects, e.g., the spread of antibiotic resistance (AR). This project builds on the PI’s previous and ongoing efforts in investigating AM surface finishes, i.e., paints, and cleaning products. This fits into the PI’s greater research program, which develops a more thorough understanding of the unintended consequences of anthropogenic chemicals on in situ microbial communities. The overarching hypotheses are 1) that bioavailability of AMs changes under environmental conditions (e.g., presence of water) and 2) that exposure to AMs produces changes in bacterial communities, including enrichment of AR. This work is tightly integrated with an outreach project to engage design professionals and the public about building materials, chemicals, and the indoor microbiome, both to ensure that relevant materials are examined and to promote education among stakeholders. Research Objective 1: Determine the composition and bioavailability of AMs in textiles. AMs will be identified and quantified using mass spectrometry. Partitioning of the AM out of the textile into the aqueous phase will be measured in dry and wet conditions and at varying temperatures. These data are needed to model the fate of chemicals indoors and determine bioavailability. Research Objective 2: Determine impact of AMs on the indoor microbiome. The effects of AMs on indoor bacteria will be examined by exposing reduced-complexity communities of undomesticated built environment isolates to these materials. Effects on AR will be measured using phenotypic and transcriptomic indicators. This work encompasses culture-based and culture-free analyses. Outreach/Education Objective 1: Integrate design professionals into research, education. Collaborators at architecture firms will be engaged to inform experimental design and dissemination of findings through interdisciplinary workshops, curriculum development, and continuing education units for architects. Outreach/Education Objective 2: Disseminate information to consumers via Wikipedia. Undergraduate and graduate students will be trained in science communication. Wikipedia edit-a-thons will be hosted to improve pages related to indoor environmental quality. Intellectual Merit The efficacy of AMs is currently unproven, yet they are widely used particularly in the current COVID-19 pandemic. This work determines whether synthetic AMs in textiles are effective in reducing microbial biomass without enriching for AR. This project will yield a more holistic perspective on the impacts of AM materials, allowing the assessment of their effects on undomesticated