Methods for the synthesis of lactic acid using crabtree-negative yeast transformed with the lactate dehydrogenase gene
View Patent ↗The invention provides methods and materials related to the production of lactic acid. Specifically, the invention provides methods for producing lactic acid using a crabtree-negative yeast, such as of the Kluyveromyces, Pichia, Candida, Trichosporon and Yamadazmya genera, which have been transformed with a lactate dehydrogenase gene.
1. A method for making lactic acid, said method comprising:
a) providing a microorganism exhibiting a crabtree-negative phenotype and transformed with at least one exogenous gene encoding lactate dehydrogenase;
b) culturing the crabtree-negative microorganism in a first culture medium which includes a carbon source under a first set of culture conditions which promote cellular respiration; and
c) culturing the crabtree-negative microorganism in a second culture medium which includes a carbon source under a second set of culture conditions which promote production of lactic acid.
2. A method for making lactic acid, comprising
a) providing a microorganism exhibiting a crabtree-negative phenotype selected from the group consisting of Kluyveromyces, Pichia, Candida and Hansenula and transformed with at least one exogenous gene encoding lactate dehydrogenase;
b) culturing said crabtree-negative microorganism in a first culture medium which includes a carbon source comprising glucose and under a first set of culture conditions, including a dissolved oxygen content of at least 20 percent relative to the amount present at saturated conditions with air at atmospheric pressure, which promote cellular respiration; and
c) then culturing the crabtree-negative microorganism in a culture medium which includes a carbon source comprising glucose under a second set of culture conditions, including a dissolved oxygen content of less than 2.0 percent relative to the amount present at saturated conditions with air at atmospheric pressure, which promote the production of lactic acid.
3. A method for making lactic acid, comprising
a) providing a microorganism exhibiting a crabtree-negative phenotype selected from the group consisting of Kluyveromyces, Pichia, Candida and Hansenula and transformed with at least one exogenous gene encoding lactate dehydrogenase;
b) culturing said crabtree-negative microorganism in a first culture medium which includes a carbon source comprising glucose and under a first set of culture conditions which promote cellular respiration; and
c) then culturing the crabtree-negative microorganism in a culture medium which includes a carbon source comprising glucose under a second set of culture conditions, including an acidic pH of greater than 1.5, which promote the production of lactic acid.
4. A method for making lactic acid, comprising
a) providing a microorganism exhibiting a crabtree-negative phenotype selected from the group consisting of Kluyveromyces, Pichia, Candida and Hansenula and transformed with at least one exogenous gene encoding lactate dehydrogenase and having a reduced pyruvate decarboxylase activity;
b) culturing said crabtree-negative microorganism in a first culture medium which includes a carbon source comprising glucose and under a first set of culture conditions which promote cellular respiration; and
c) then culturing the crabtree-negative microorganism in a culture medium which includes a carbon source comprising glucose under a second set of culture conditions which promote the production of lactic acid.