ABSTRACT

Compounds known as condensed tannins (CTs) impact the ability of microbial communities to synthesize biofuels, detoxify industrial waste streams, perform critical carbon cycling in soils, and fuel nutrition in humans and animals. Despite their global importance, microbial responses to CTs are currently a mystery. This research project targets this substantial knowledge gap to identify the microorganisms and their enzymes that degrade CTs across a range of ecosystems. Beyond scientific advances, this project will also support significant curricular development in the introductory microbiology course at The Ohio State University. Through the development of a Course-based Undergraduate Research Experience (CURE), this project will allow hundreds of undergraduate student-scientists to perform authentic research; experiences shown to enhance scientific education and boost retention of students in scientific disciplines. This project will create a modified undergraduate laboratory class where CURE students participate in the discovery and classification of CT degrading microorganisms new to science, generating data that will be integrated into the research aims of this project. Additionally, the scientific data generated here will be transmitted more broadly to the scientific community via the production of an interactive, web-based bioinformatics platform. As part of the integrated research and educational objectives, this research will generate fundamental knowledge of CT-microbe interactions with direct applications to agricultural, industrial, and health resource management.

Today the diversity of microorganisms, enzymes, and pathways mediating microbial CT degradation are currently unknown. The overarching goal of this research project is to test the central hypothesis that mechanisms for tolerance and degradation of CTs are widely encoded in microbial genomes across ecosystems, yet currently represent a cryptic microbial metabolism. This project tracks CT metabolism from organismal to ecosystem scales, identifying the enzymatic catalysts of organismal CT tolerance and degradation, the coordinated responses to CT perturbation in microbial communities, and the extent of CT metabolisms across ecosystems. Here, parallel isolate and community genomics paired to expression analyses and high-resolution CT metabolite data will elucidate the organisms, enzymes, and metabolisms mediating CT degradation and resistance. Outcomes from this research project include (1) knowledge of the microbial physiology and ecology of CTs, (2) discovery of novel degradative enzymes that are likely common to anaerobic microorganisms, (3) development of a CT library of biological and metabolite signatures resulting in the identification of microbial polyphenolics and their degradation products.

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