Development of a Carbon Conserving Microbial pathway for the conversion of lignocellulosic biomass-derived C5 sugars to a/w-difunctional chemicals. Topic/Subtopic: C43/22e

Period of Performance: 02/21/2017 - 02/20/2018


Phase 1 SBIR

Recipient Firm

4 Anchor Drive Suite 231
Emeryville, CA 94608
Firm POC, Principal Investigator


Establishing a global bio-based economy will require breakthrough biotechnologies for the production of both fuels and industrial chemicals, wherein these biotechnologies will need to be cost-advantaged with today’s state-of-the-art petroleum-based production processes. Two key features of such biotechnologies include [1] developing bioprocesses that can use all available forms of carbon from lignocellulosic feedstocks, and [2] maximizing the the carbon efficiency during the conversion processes. For example, when microbes use bio-based feedstocks to make more reduced chemicals, deoxygenation most often occurs via the loss of ≥33% of the sugar’s carbon as carbon dioxide (CO2), limiting the theoretical yields to ≤67%. This carbon loss as CO2 generally precludes profitability for many bio-based endeavors, as feedstocks typically account for more than half of the total costs of a bioprocess. Additionally, many of today’s bioprocesses and engineered microbes are tailored to utilize C6 sugars (i.e., glucose). In turn, the microbes are highly inefficient at using other carbon sources such as C5 sugars (D-xylose and L-arabinose), which constitute >33% of the sugars in lignocellulose-based feedstocks – the most abundant non-edible biomass. Utilization of these C5 sugars is critical for the economic viability of bio-refineries that use lignocellulose- derived sugars for the production of fuels and chemicals. While there has been substantial progress in lignocellulose-based ethanol production, it will be crucial to develop new microbial-based platforms that expand the range of products that can be made from lignocellulosic sugars – particularly the C5 sugars – and in a carbon-efficient manner. At ZymoChem, we have established a two-part solution to this problem. For the first part, we are developing a carbon conserving (C2) technology to avoid CO2 production when microbes convert bio-based feedstocks into chemicals. Our novel C2 technology is a collection of biosynthetic pathways for making chemicals without losing the feedstock carbon as CO2, in turn increasing theoretical yields up to 50%. This improvement in carbon-efficiency creates an opportunity to significantly reduce overall production costs, thus improving the feasibility to supplant state-of-the-art petroleum-based processes. For the second part of our solution, microbes with our C2 technology will be designed to utilize C5 sugar-rich streams (e.g., hemicellulose-based hydrolysates) for producing a suite of industrially relevant chemicals. This aspect is particularly appealing since several leading lignocellulose pretreatment technologies produce separate C5 and C6 sugar streams. In turn, this creates a need for biotechnologies that [1] are tailored to use sugar streams that contain mostly C5 sugars such as D-xylose and L-arabinose, and [2] complement existing glucose-based biotechnologies to enable the use of C6 sugar streams for producing industrial chemicals. Notably, our team at ZymoChem has designed and validated our C2 technology in E. coli for utilizing C5 sugars to target several industrially relevant C5 ,-difunctional chemicals. During this SBIR Phase I project, we will develop our unique pentose-based C2 technology in Saccharomyces cerevisiae for the production of glutaric acid – our first C5 ,-difunctional product – from D-xylose, the most abundant C5 sugar. Acid-tolerant industrial microbes like S. cerevisiae are preferred hosts for producing dicarboxylic acids such as glutaric acid, though S. cerevisiae is known to be inefficient at assimilating C5 sugars. Strains of S. cerevisiae previously engineered for increased rates of D-xylose uptake (available for licensing under this TTO) could provide a general solution to this pentose-uptake limitation and are thus promising candidates for developing our pentose-based C2 relevant host.