Development and analysis of novel microbial platforms for Syngas to biofuels and high value chemicals

Technologies for the conversion of renewable biomass feedstocks to biofuels and value-added chemicals are currently limited by feedstock heterogeneity and recalcitrance. The most common forms of biomass feedstocks for microbial conversion are complex, with multiple steps that increase cost, waste, and likelihood of contamination. Alternatively, biomass can be converted in a single step via gasification to syngas, a more homogenous substrate that consists primarily of CO and H₂, which can be utilized by one microbe in one reactor. To date, the biological conversion of gasified biomass into fuels is limited by the lack of robust, syngas-utilizing microbes that are fast-growing, easy to engineer, and are tolerant of syngas impurities. Chemical methods to produce fuels from syngas are limited by impurities as well. To address these issues, Kiverdi and the National Renewable Energy Laboratory are working in concert to analyze a number of potential syngas-utilizing platform strains. This analysis will identify the best strains for the production of terpenes and other chemicals. First, we performed comparative analysis of growth conditions and utilization of/tolerance to CO. Since many of these organisms lack an established genetic system, we are also developing a standard system based on other successes we have had with difficult to engineer microbes to establish basic and essential genetic engineering capabilities for transformation, stable plasmid-based expression, and targeted gene knock-outs/knock-ins. Our ultimate goal is to develop the best syngas microbe for the production of limonene, a next-generation terpenoid biofuel, through the heterologous expression of an optimized enzyme.