CAREER: Expanding and controlling the product spectrum from anaerobic bioprocessing of wastes

Microbiome-based processes are increasingly being utilized by environmental engineers to recover valuable resources from organic wastes. For example, anerobic digestion is used to generate biogas for heating, electricity generation, and to produce methane. Anaerobic digestion with chain elongation has emerged as a promising environmental biotechnology platform for converting organic wastes to high-value chemicals that can serve as chemical building blocks for the manufacturing of polymers and industrially relevant products.

During chain elongation, microorganisms combine volatile fatty acids generated from the anaerobic digestion of organic substrates with electron donors such as ethanol or acetate to produce longer chain chemicals. However, the ability to tune and control the product spectrum of chain-elongating microbiomes has remained elusive. The overarching goal of this CAREER project is to advance the fundamental understanding of these microbiomes with the ultimate goals of developing new and optimal feedstocks and reactors to tune and control their product distributions.

The successful completion of this project will benefit society through the generation of new fundamental knowledge to advance the development of a circular bioeconomy using organic wastes as feedstocks. Further benefits to society will be achieved through student education and training including the mentoring of a graduate student and an undergraduate student at the University of Vermont.

Organic wastes such as food and agricultural residues can be converted into high value chemicals such as medium-chain carboxylic acids (MCCAs) using anaerobic digestion with chain elongating microbiomes. However, there are critical knowledge gaps in the fundamental understanding of MCCA generation by chain elongating microbiomes. First, the potential of protein-rich feedstocks for MCCA production is not well understood.

Second, the ability to control and tune reverse beta-oxidation pathways that drive the production of MCAAs by chain elongation has remained elusive. Third, tools for modeling MCCA production from complex organic feedstocks are only beginning to emerge. This CAREER proposal will address these critical knowledge gaps.

The guiding hypothesis of the proposed research is that anaerobic microbiomes can be controlled and steered to generate MCCAs in a predictable way using amino acid and protein feedstocks. The specific objectives of the proposed research are to: (1) Evaluate amino acid and protein rich substrates and new feeding strategies to tailor and control MCCA production, (2) Design and evaluate new bioreactors for improved MCCA production and extraction, and (3) Develop computational tools to model chain elongation bioprocesses.

The successful completion of this project has the potential for transformative impact through the generation of new fundamental knowledge to advance the development of more efficient and cost-effective bioprocesses to recover valuable chemicals from organic wastes while reducing their environmental impact. To implement the educational and training goals of this CAREER project, the Principal Investigator (PI) will work with the University of Vermont (UVM) Extension 4-H to teach and inspire high school students to explore the use of microbiomes to protect the environment and public health.

In addition, the PI plans to develop and teach two new courses at UVM including a course-based undergraduate research experience that focuses on the circular bioeconomy (biorefining) and a graduate course to prepare environmental engineering students to use ‘omic’ technologies and computational tools to characterize and simulate microbiomes of environmental relevance.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.