Patent ID: 8455239
Filing Date: 2013-06-04
Classification: C12N,C12P,C12Y,Y02E

Abstract:
1. A recombinant yeast microorganism for producing isobutanol, the recombinant yeast microorganism comprising an isobutanol producing metabolic pathway, wherein said isobutanol producing metabolic pathway comprises the following substrate to product conversions: (i) pyruvate to acetolactate; (ii) acetolactate to 2,3-dihydroxyisovalerate; (iii) 2,3-dihydroxyisovalerate to α-ketoisovalerate; (iv) α-ketoisovalerate to isobutyraldehyde; and (v) isobutyraldehyde to isobutanol; wherein the recombinant yeast microorganism expresses (a) an acetolactate synthase to catalyze the conversion of pyruvate to acetolactate; (b) a ketol-acid reductoisomerase to catalyze the conversion of acetolactate to 2,3-dihydroxyisovalerate; (c) a dihydroxyacid dehydratase to catalyze the conversion of 2,3-dihydroxyisovalerate to α-ketoi sovalerate; (d) an α-ketoisovalerate decarboxylase from (e) an alcohol dehydrogenase to catalyze the conversion of isobutyraldehyde to isobutanol; wherein the recombinant yeast microorganism has been engineered to: (A) disrupt, mutate, or delete one or more endogenous pyruvate decarboxylase (PDC) genes; and (B) disrupt, mutate, or delete one or more endogenous glycerol-3-phosphate dehydrogenase (GPD) genes; wherein said recombinant yeast microorganism has reduced endogenous PDC and reduced endogenous GPD activity as compared to the corresponding yeast microorganism that has not been engineered to have reduced endogenous PDC activity and reduced endogenous GPD activity; and wherein the recombinant yeast microorganism produces isobutanol at a yield which is at least 10% of the theoretical yield of isobutanol from glucose.