Modified yeast and method for increasing lysine content in fermentation co-products
AssigneeDanisco US Inc.
InventorsJaclyn Diana DeMartini, Celia Emily Gaby Payen
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Abstract
Described are strains and methods relating to genetically-engineered yeast cells that overproduce lysine in a tunable manner by altering feedback inhibition of the lysine synthetic pathway by way of the LYS20 and LYS21 homocitrate synthase polypeptides. The yeast can be used in a conventional bioethanol production facility to produce alcohol along with increased amounts of lysine, resulting in increased quality and commercial value of fermentation products and co-products, such as animal feed ingredients.
Claims19
A non-naturally-occurring variant homocitrate synthase polypeptide having at least 80% amino acid sequence identity to SEQ ID NO:
- 1 and comprising one or more mutations selected from the group consisting of N52D, D125N, R289I, N303D and N393D, with respect to SEQ ID NO:
- 1, wherein the variant homocitrate synthase polypeptide demonstrates reduced lysine inhibition compared to an otherwise identical homocitrate synthase polypeptide lacking the one or more mutations.
A method for increasing the amount of lysine present in a post-fermentation product from an ethanol production facility, comprising:
- (i) hydrolyzing a starch-containing feedstock with an α-amylase to produce a starch liquefact;
- (ii) saccharifying the starch liquefact with a glucoamylase to produce glucose;
- (iii) fermenting the glucose with modified yeast cells derived from parental yeast cells, the modified yeast cells comprising a genetic alteration that reduces feedback inhibition of the lysine production pathway as mediated through homocitrate synthase polypeptides in the lysine production pathway;
- and
- (iv) recovering post-fermentation by-product enriched for lysine compared to post-fermentation by-products recovered from an otherwise identical process using the parental yeast.
A method for increasing the amount of lysine present in a fermentation product, comprising:
- (i) fermenting glucose or another sugar with modified yeast cells derived from parental yeast cells, the modified yeast cells comprising a genetic alteration that reduces feedback inhibition of the lysine production pathway as mediated through homocitrate synthase polypeptides in the lysine production pathway;
- and
- (ii) recovering fermentation product enriched for lysine compared to a fermentation product recovered from an otherwise identical process using the parental yeast.
Dependencies are inferred from the claim text.