A study chronicled in Metabolic Engineering, reported that the US Department of Energy’s BioEnergy Science Center (BESC) has developed a microbe, which is claimed to increase isobutanol yield ten-fold. The latest breakthrough follows the first genetically engineered microbe, Clostridium celluloyticium, to produce isobutanol directly from cellulose. James Liao, UCLA’s Henry Samueli School of Engineering and Applied Science co-author, et al., engineered similar traits in the much higher yielding Clostridium thermocellum, which enabled them to achieve consolidated bio-processing efficiency.
The researchers used five genes with the microbe, and identified that Clostridium thermocellum produced around 6g of isobutanol per litre. With the previous genetically engineered microbe, they achieved conversion results of 0.6g per litre. This development moved the BESC team closer to the production goal of more than 20g per litre. The prospects of commercial realisation of this approach are greatly enabled by the fact that the microbe works at temperatures high enough to keep competing bugs from contaminating the microbial fermentation tanks and interfering with the conversion process. Consolidated bio-processing involves integrating various processes in a single microbe to extract sugar from cellulose and convert those sugars into a biofuel. Isobutanol exhibits similar energy density and octane values as gasoline, and is used as a chemical feedstock for various products.