Yeast cells having disrupted pathway from dihydroxyacetone phosphate to glycerol

Abstract

Yeast cells are genetically modified to disrupt a native metabolic pathway from dihydroxyacetone to glycerol. In certain aspects, the yeast cell is of the genera Kluyveromyces, Candida or Issatchenkia . In other aspects, the yeast cell is capable of producing at least one organic acid, such as lactate. The yeast cells produce significantly less glycerol than the wild-type strains, and usually produce greater yields of desired fermentation products. Yeast cells of the invention often grow well when cultivated, despite their curtailed glycerol production.

1 - 60 . (canceled) 
     
     
         61 . A fermentation process wherein a cell is cultivated in a fermentation medium under fermentation conditions and in the presence of a carbon source and added glycerol to produce a desired fermentation product, wherein the glycerol yield is less than 2% based on the weight of the carbon source that is consumed by the cell, wherein the cell is a cell of a pre-whole genome duplication hemiascomycetous yeast, in which the entire coding region of at least one native glycerol-3-phosphate dehydrogenase gene has been eliminated or the coding region, promotor or terminator region of at least one native glycerol-3-phosphate dehydrogenase gene has been modified by deletion or insertion so the native glycerol-3-phosphate dehydrogenase gene no longer produces an active glycerol-3-phosphate dehydrogenase enzyme. 
     
     
         62 . The fermentation process of  claim 61  wherein the desired fermentation product is produced in a yield of at least 40% based on the weight of the carbon source that is consumed by the cell. 
     
     
         63 . The process of  claim 62 , wherein the glycerol yield is less than 0.5% based on the weight of the carbon source that is consumed by the cell. 
     
     
         64 . The process of  claim 63 , wherein the desired fermentation product is ethanol. 
     
     
         65 . (canceled) 
     
     
         66 . The fermentation process of  claim 61  wherein the desired fermentation product is an organic acid, the organic acid is produced in a yield of at least 40% based on the weight of the carbon source that is consumed by the cell and the glycerol yield is less than 0.5% based on the weight of the carbon source that is consumed by the cell. 
     
     
         67 - 69 . (canceled) 
     
     
         70 . The fermentation process of  claim 61 , in which the cell is within the  Zygosaccharomyces, Zygotorulaspora, Torulaspora, Lachancea, Kluyveromyces, Eremothecium  or  Hanseniaspora  clades of the  Saccharomyces  complex. 
     
     
         71 . The fermentation process of  claim 61 , in which the cell is of the genera  Kluyveromyces, Candida  or  Issatchenkia.    
     
     
         72 . The fermentation process of  claim 61 , in which the cell is within the  I. orientalis/P. fermentans  clade or within the  Kluyveromyces  clade of the  Saccharomyces  complex. 
     
     
         73 . The fermentation process of  claim 61 , in which the cell is  Issatchenkia orientalis, Pichia galeiformis, Pichia  sp. YB-4149 (NRRL designation),  Candida ethanolica, P. deserticola, P. membranifaciens, P. fermentans, S. kluyveri, K. aestuaryii, K. nonfermentans, K. lactic, K. marxianus  or  K. dobzhanskii.    
     
     
         74 . The fermentation process of  claim 66 , in which the cell is within the  Zygosaccharomyces, Zygotorulaspora, Torulaspora, Lachancea, Kluyveromyces, Eremothecium  or  Hanseniaspora  clades of the  Saccharomyces  complex. 
     
     
         75 . The fermentation process of  claim 66 , in which the cell is of the genera  Kluyveromyces, Candida  or  Issatchenkia.    
     
     
         76 . The fermentation process of  claim 66 , in which the cell is within the  I. orientalis/P. fermentans  clade or within the  Kluyveromyces  clade of the  Saccharomyces  complex. 
     
     
         77 . The fermentation process of  claim 66 , in which the cell is  Issatchenkia orientalis, Pichia galeiformis, Pichia  sp. YB-4149 (NRRL designation),  Candida ethanolica, P. deserticola, P. membranifaciens, P. fermentans, S. kluyveri, K. aestuaryii, K. nonfermentans, K. lactic, K. marxianus  or  K. dobzhanskii.