Method for producing lactic acid in recombinant yeast cell culture
AssigneeSyconium Lactic Acid GmbH
InventorsMagnus Ask, Rakesh Koppram, Diethard Mattanovich, Michael Sauer
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Abstract
The present invention provides a method for producing lactic acid in a recombinant yeast cell culture using glucose as carbon source comprising a first, seed fermentation stage to produce biomass wherein the yeast is cultivated in a culture medium at a pH of 5 to 7, followed by a second, a production fermentation stage with biomass from the seed fermentation to produce lactic acid, wherein the yeast is cultivated in a culture medium at low p H using a yeast strain that is engineered to have lactate dehydrogenase (LDH) activity and optionally has decreased or knocked-out pyruvate decarboxylase (PDC) activity.
Claims14
A method for producing lactic acid in a recombinant yeast cell culture using glucose as carbon source, comprising:
- a) cultivating an at least diploid yeast in a seed fermentation stage to produce biomass, wherein the yeast is cultivated in a culture medium at a pH of 5 to 7, followed by
- b) cultivating said yeast in a production fermentation stage with biomass from the seed fermentation stage to produce lactic acid, wherein the yeast is inoculated at a cell density of at least an OD600 of 5 and cultivated in a culture medium at a pH of <5 until reaching a final pH of <3.5, and
- wherein said yeast is S. cerevisiae strain CBS7962 and expresses Lactobacillus plantarum lactate dehydrogenase (LDH), wherein said yeast strain has knocked out expression of PDC1, PDC5 and PDC6 genes, and wherein the seed fermentation stage and the production fermentation stage are in separate fermenters.
A two part fermentation system for producing lactic acid with glucose as carbon source using a recombinant yeast strain, wherein the yeast strain is at least diploid, consisting of:
- a) a seed fermentation stage to produce biomass, wherein the yeast cells are cultivated in a cell culture medium at a pH of 5 to 7, and
- b) a production fermentation stage to produce lactic acid, wherein the yeast cells are cultivated in a cell culture medium until a final pH of less than 3.5, <3.4, <3.3, <3.2, <3.1, <3.0, <2.9, <2.8, <2.7, <2.6, <2.5, <2.4, <2.3, <2.2, or <2.15
- wherein said yeast strain is S. cerevisiae strain CBS7962 and expresses Lactobacillus plantarum lactate dehydrogenase (LDH) activity, and wherein said yeast strain has knocked out expression of PDC1, PDC5 and PDC6 genes.
Dependencies are inferred from the claim text.