The development of breakthrough biotechnologies for the production of fuels and chemicals along with commercializing bioprocesses that are cost-competitive with existing petroleum-based processes will be necessary to establish a sustainable bio-based economy- Two crucial biotechnologies to achieve this include processes that can utilize all forms of carbon available in lignocellulosic feedstocks and approaches that maximize the carbon efficiency of conversion processes- When microbes use bio-based feedstocks to make more reduced chemicals, deoxygenation most often occurs via the loss of ?33% of the feedstocks carbon in the form of carbon dioxide (CO2), limiting the maximum achievable theoretical yields to ?67%- Given that feedstocks typically account for more than half of the total costs of a bioprocess, the carbon lost as CO2 generally precludes profitability for many bio-based endeavors- Additionally, such carbon-inefficient microbial approaches that exist today are tailored for using six-carbon (C6) sugars as feedstock carbon and typically suffer from poor utilization of other carbon sources such as five- carbon (C5) sugars (e-g-, D-xylose and L-arabinose), which constitute >33% of the sugars in lignocellulosic feedstocks the most abundant inedible form of biomass- Utilization of these C5 sugars is critical to the economic viability of biorefineries that use sugars derived from lignocellulosic biomass for producing of fuels and chemicals- Although there has been remarkable progress in lignocellulosic-based ethanol production, there remains a need for the development of new metabolic platforms that expand the range of bioproducts that can be made via engineered microbes and using lignocellulosic C5 sugars, - To address these biotechnology needs, we have developed a carbon conserving (C2) biosynthetic pathway technology that can convert lignocellulosic C5 sugars (i-e-, pentoses) to a range of industrially desired C5 ???- difunctionalchemicals, specificallywithnolossofcarbonasCO2-OurnovelC2technology increases theoretical yields up to 50%, thus providing an opportunity to supplant state-of-the-art petroleum-based production methods, while also establishing the capability to use under-utilized lignocellulosic C5 sugars as feedstocks for chemicals production-
