We are developping our growth-arrested bioprocess for highly efficient production of biobutanols (isobutanol and n-butanol) by metabolic engineering of microorganism introducing butanol biosynthetic pathways. Butanols are superior to ethanol as alternative vehicle fuels, and expected to be next-generation renewable jet fuels through chemical conversion such as dehydration, oligomerization, and hydrogenation. Butanols are also converted to various chemicals.

<Biobutanol production process>

AHAIR is an NADPH-dependent enzyme in isobutanol biosynthetic pathway. As NADH but NADPH is a major redox cofactor regenerated in anaerobic fermentation, AHAIR is unable to work efficiently in growth-arrested bioprocess. To overcome this problem, we genetically modified cofactor-preference of AHAIR to obtain a NADH-dependent one named as IlvCTM, which successfully led to efficient production of isobutanol in growth-arrested bioprocess.

<Isobutanol biosynthetic pathway>