Patent ID: 7993889

Claim:
A method for producing isobutanol comprising; a. providing a fermentation media comprising carbon substrate; and b. contacting said media with a recombinant yeast microorganism expressing an engineered isobutanol biosynthetic pathway wherein said pathway comprises the following substrate to product conversions; i. pyruvate to acetolactate (pathway step a); ii. acetolactate to 2,3-dihydroxyisovalerate (pathway step b); iii. 2,3-dihydroxyisovalerate to α-ketoisovalerate (pathway step c); iv. α-ketoisovalerate to isobutyraldehyde (pathway step d); and v. isobutyraldehyde to isobutanol (pathway step e); and wherein a) the substrate to product conversion of step (i) is performed by an acetolactate synthase enzyme; b) the substrate to product conversion of step (ii) is performed by an acetohydroxy acid isomeroreductase enzyme; c) the substrate to product conversion of step (iii) is performed by an acetohydroxy acid dehydratase enzyme; d) the substrate to product conversion of step (iv) is performed by a decarboxylase enzyme; and e) the substrate to product conversion of step (v) is performed by an alcohol dehydrogenase enzyme; whereby isobutanol is produced.