Yeast with increased butanol tolerance involving cell wall integrity pathway

A recombinant yeast cell comprising:

• a) an isobutanol biosynthetic pathway, wherein the isobutanol biosynthetic pathway comprises at least one gene encoding a polypeptide that performs at least one of the following substrate to product conversions:
• i) pyruvate to acetolactate, as catalyzed by acetolactate synthase;
• ii) acetolactate to 2,3-dihydroxyisovalerate, as catalyzed by acetohydroxy acid isomeroreductase;
• iii) 2,3-dihydroxyisovalerate to α-ketoisovalerate, as catalyzed by dihydroxyacid dehydratase;
• iv) α-ketoisovalerate to isobutyraldehyde, as catalyzed by branched-chain keto acid decarboxylase;
• and
• v) isobutyraldehyde to isobutanol, as catalyzed by a branched-chain alcohol dehydrogenase;
• and
• b) at least one genetic modification which increases cell wall integrity pathway activity, wherein the genetic modification increases activity of a mitogen-activated protein kinase module of the cell wall integrity pathway, and wherein the genetic modification is overexpression of a STL2 protein encoding gene;
• wherein the isobutanol biosynthetic pathway comprises at least one gene that is heterologous to the yeast cell and wherein the yeast cell has an increase in tolerance to isobutanol and at least a 20% improvement in growth yield as compared with a yeast cell that lacks the at least one genetic modification of (b).