Yeast production host cells

摘要

Crabtree positive yeast cells that have endogenous expressed pyruvate decarboxylase genes inactivated and an engineered biosynthetic pathway utilizing pyruvate were found to have improved growth and product yield when glucose repression was reduced. These cells were able to grow in media containing a high glucose concentration.

主权项

1. A recombinant yeast production host cell comprising:
(a) a first genetic modification, which has the effect of reducing glucose repression, wherein the first genetic modification is a deletion in at least one endogenous gene encoding a hexokinase enzyme that has nuclear and cytoplasmic localization, wherein the deletion eliminates the activity of the hexokinase enzyme; and (b) a second genetic modification, wherein the second genetic modification is a deletion in at least one endogenous gene encoding a pyruvate decarboxylase enzyme, wherein the deletion eliminates pyruvate decarboxylase activity; and (c) a pyruvate utilizing biosynthetic pathway, wherein the pyruvate utilizing biosynthetic pathway is an isobutanol biosynthetic pathway comprising heterologous DNA molecules encoding polypeptides that catalyze 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; andv) isobutyraldehyde to isobutanol; wherein the yeast production host cell produces isobutanol, andwherein growth of the recombinant yeast production host cell is improved at least 2-fold as compared to a recombinant yeast production host cell without the first genetic modification.