I-Corps: Catalytic Artificial Self-Assemblies for the Biocatalytic Production of Small Molecules

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

The broader impact/commercial potential of this I-Corps project is the development of a class of synthetic cells that can replace conventional biocatalytic processes for chemical production. Currently, biocatalysis of small molecules is implemented by two main methods: whole-cell catalysis and cell-free catalysis, both of which have their advantages and challenges. Whole-cell catalysis is limited in production metrics by the accumulation of toxins. In contrast, cell-free systems can support higher production metrics but suffer from enzyme degradation, which makes the manufacturing of complex chemicals difficult and economically unfeasible. The proposed technology provides an intermediate route to alleviate these challenges, and may be used to produce small molecules currently manufactured from conventional biocatalytic means, such as food additives and fragrances, drug precursors, and biofuels. For example, the proposed technology may be used to produce isobutanol from lignocellulose, which is considered the next generation of biofuels. Lignocellulose is the largest naturally available feedstock and is not derived from food sources, eliminating concerns about biofuel competition with food production. Compared with conventional ethanol biofuels, isobutanol may be blended with gasoline at higher concentrations and used directly in the existing petroleum infrastructure. The proposed technology is expected to achieve a 95% isobutanol yield from saccharified lignocellulose concentrations due to its improved tolerance compared to microbes, and lower greenhouse gas emissions by >70%, which cannot be achieved by conventional methods. This I-Corps project is based on the development of colloidal materials, called catalytic artificial self-assemblies (CASA), which are synthetic cells for the biocatalytic production of small molecules. The proposed technology uses complex coacervate protocells prepared and stabilized using low-cost, commercially available polymers. Simplified complex coacervate protocells have been shown to preserve enzymes in their near-native environments while still providing the flexibility of cell-free systems. Protocells of complex coacervate microdroplet emulsions improve enzymatic reaction rates by up to 25-fold and provide long-term stability (~4 months) to enzymes as well as processing flexibility not accessible in cells. In addition to showing improved reaction metrics, CASA is robust to environmental perturbations and overcomes key challenges concerning cell toxicity in whole cell systems, and enzyme stability in cell-free systems. This may allow a more flexible and economical bioreactor design and scaling up of these processes where the proposed platform may be used as a standalone method or integrated into existing industrial pipelines to reduce the cost of chemical production. 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.