Patent ID: 8530226
Filing Date: 2013-09-10
Classification: C12N,C12P,Y02E

Abstract:
1. A yeast cell producing isobutanol, characterized in that the cell has an increased metabolic flow of material from pyruvate via acetolactate, 2,3-dihydroxy isovalerate, 2-ketoisovalerate, isobutyraldehyde to isobutanol, in that at least one of the genes which code for the enzymes which are involved in this conversion is over-expressed and without any of these genes being heterologous to the said yeast cell, wherein Ilv2 (=YMR108W) (SEQ. ID. no. 2) catalyzes the acetolactate synthase reaction from pyruvate to acetolactate, Ilv5 (=YLR355C) (SEQ. ID. no. 6) catalyzes the acetohydroxy acid reducto-isomerase reaction from acetolactate to 2,3-dihydroxy isovalerate, Ilv3 (=YJR016C) (SEQ. ID. no. 8) catalyzes the dihydroxy acid dehydratase reaction from 2,3-dihydroxy isovalerate to 2-ketoisovalerate, a 2-keto acid decarboxylase catalyzes the reaction from 2-ketoisovalerate to isobutyraldehyde, characterized in that the 2-keto acid decarboxylase is selected from at least one of the enzymes Aro10 (SEQ. ID no. 20) or Thi3 (SEQ. ID. no. 22), and an alcohol dehydrogenase catalyzes the reaction from isobutyraldehyde to isobutanol, characterized in that the alcohol dehydrogenase is selected from at least one of the enzymes Adh1 (SEQ. ID no. 24), and Adh2 (SEQ. ID. no. 26). Adh3 (SEQ. ID. no. 28), Adh4 (SEQ. ID. no. 30), Adh5 (SEQ. ID. no. 32), Adh6 (SEQ. ID. no. 34), Adh7 (SEQ. ID. no. 36), Sfa1 (SEQ. ID. no. 38) or Ypr1 (SEQ. ID. no. 40), wherein either at least one of the promoters of these genes is exchanged for at least one stronger promoter or the nucleic acid sequences of these genes are converted into codon-optimized alleles; characterized in that the enzymes acetolactate synthase, acetohydroxy acid reducto-isomerase and dihydroxy acid dehydratase are located in the cytosol of the cell.