(567ao) Rhodospirillum Rubrum as a Model Organism for the Conversion of Carbon Monoxide to Biofuels

Synthesis gas (Syngas) can be produced from any organic material including all forms of biomass permitting it to become a significant source of feedstock for the production of fuels and chemicals. One of the major components of syngas is carbon monoxide (CO) in addition to hydrogen and smaller amounts of carbon dioxide. The goal of this study was to develop a platform microorganism that is capable of fermenting syngas and is also amenable to genetic engineering. To accomplish this we utilized Rhodospirillum rubrum as the model microorganism. Experiments were conducted to show R. rubrum's utilization of CO as the sole carbon and energy source in dark conditions. A series of toxicity assays were conducted that showed the ability of R. rubrum's growth in the presence of 2% (w/v) ethanol, isopropanol, n-butanol and isobutanol. Genetic engineering included the chromosomal integration of Zymomonas mobilis alcohol dehydrogenase genes for ethanol production using a transposon-based strategy. Another approach included plasmid based introduction of Clostridium acetobutylicum's n-butanol pathway in R. rubrum. Quantitative-PCR was used to verify the transcriptional expression of the selected genes. Ongoing work includes targeted deletions to increase alcohol production and codon-optimized synthesis of genes for better enzyme activity, to be followed by fermentation validation.