Filling the gaps to find new sources of energy

There are countless reasons why there is an increasing need for low-cost fuels and chemicals from sustainable resources. The world’s population is growing, the standard of living is on an upward trajectory, the market remains highly competitive, and resource scarcity is increasingly problematic, to name a few.

One potential solution comes from industrial biotechnology’s use of microbial cell factories, which offer advantages over distributed manufacturing and an opportunity to reduce or even capture greenhouse gas emissions. Yet designing, building and optimizing biosynthetic pathways in cells remains complex, risky and time-consuming.

“These factors are exacerbated in industry-relevant non-model organisms for which genetic tools are not as sophisticated, high-throughput workflows are often lacking, and transformation idiosyncrasies exist,” Northwestern University said. Michael Jewett said. “Furthermore, most metabolic engineering efforts have primarily focused on linear heterologous pathways that limit the co-development of multiple biochemicals.”

New work from a multi-institutional team of researchers, including Jewett, could fill in some of these gaps.

Courtesy of Northwestern University

Michael Jewett is a professor and director of the Center for Synthetic Biology at Northwestern University. His lab studies how complex biological systems are designed.

Jewett and collaborators at LanzaTech and the University of South Florida have optimized and implemented a cyclic reverse beta-oxidation (r-BOX) pathway for the specific production of butanol, butanoic acid, hexanol and of hexanoic acid on three biotechnological platforms. The three platforms include a cell-free system, a heterotrophic model organism (E. coli) and an autotrophic organism (C. autoethanogenum) capable of fixing carbon and using syngas – a mixture of carbon monoxide and d hydrogen – as the only carbon and energy source.

Jewett and his teammates reported on their work in the journal Nature Communication. Jewett is Walter P. Murphy Professor of Chemical and Biological Engineering and Director of the Synthetic Biology Center. Other corresponding authors were LanzaTech Vice President for Synthetic Biology Michael Köpke and USF Professor Ramon Gonzalez.

Build on past research Posted in Natural biotechnology, where researchers selected, engineered, and optimized a bacterial strain and then successfully demonstrated its ability to produce carbon-negative acetone and isopropanol, this investigation streamlines the process and broadens the spectrum of molecules that can be produced . A key feature of their work was the creation of an automated liquid handling workflow based on cell-free biosynthesis, which was later adapted for r-BOX. This allowed the team to rapidly screen 762 unique pathway combinations to identify the optimal enzyme sets for improved product selectivity in weeks rather than months.

“Our work forms a new model for the generation and optimization of biochemical pathways for metabolic engineering and synthetic biology,” Jewett said. “This will facilitate the design-build-test cycles of biosynthetic pathways by decreasing the number of strains that need to be designed and the time required to achieve desired process goals.”

Gonzalez added, “The iterative and modular nature of r-BOX allows for the synthesis of products of different chain lengths and functionalities with high carbon and energy efficiency. This allowed us to co-develop bespoke processes for four different products, rather than just one product. r-BOX can further be extended to an array of other products of interest by leveraging the developed workflows,” the authors discussed in a separate article published in the JJournal of Industrial Microbiology and Biotechnology.

The next steps, Köpke said, are to scale up production and expand the reach of sustainable chemicals made by biology.

“LanzaTech already operates two commercial facilities that convert industrial gases into ethanol, mitigating hundreds of thousands of tons of greenhouse gas emissions,” Köpke said. “The implementation of r-BOX will increase the flexibility of biological processes to adapt to new markets, expand the range of fossil-derived products that can be replaced by bio-derived alternatives, and improve the economic benefits of co-produced fuels. ”

This article has been republished with permission from the McCormick School of Engineering at Northwestern University. Read the original.