Method for lactic acid production using
Tools and methods for producing organic acids using strains of Monascus which are tolerant to high organic acid concentrations at low pH.
1. A method of producing a composition comprising lactic acid, the method comprising:
(i) providing a Monascus micro-organism that is tolerant to organic acid at a concentration of at least 50 g/L and a pH of less than 5.0 and has been genetically modified for increased production of a lactic acid by the introduction of an exogenous lactate dehydrogenase (LDH) gene; and
(ii) culturing the micro-organism in a medium having a pH less than 1.5 units above the pKa value of lactic acid in the presence of hexose, pentose, or a combination thereof, as the sole carbon source.
2. The method of claim 1 , wherein the lactic acid is L-lactic acid.
3. The method of claim 1 , further comprising recovering the lactic acid from the medium.
4. The method of claim 1 , wherein the micro-organism has been further genetically modified to delete or inactivate an endogenous LDH gene.
5. The method of claim 1 , wherein the micro-organism has been further genetically modified to delete or inactivate a PDC1, PDC2, or PDC4 gene.
6. The method of claim 1 , wherein: the micro-organism has been genetically modified to delete or inactivate a gene encoding pyruvate decarboxylase, fumarate reductase, alcohol dehydrogenase, acetaldehyde dehydrogenase, phosphoenolpyruvate carboxylase, D-lactate dehydrogenase, L-lactate dehydrogenase, or lactate 2-monooxygenase.
7. The method of claim 6 , wherein the micro-organism has been genetically modified to delete or inactivate a gene encoding pyruvate decarboxylase, D-lactate dehydrogenase, or L-lactate dehydrogenase.
8. The method of claim 1 , wherein the lactic acid is produced at a yield of at least 0.5 g/L.
9. The method of claim 8 , wherein the yield is at least 2 g/L.