Genetically modified yeasts and fermentation processes using genetically modified yeasts

Abstract

The present invention relates to a genetically engineered yeast capable of manufacturing a fermentation product using sucrose as a fermentation substrate, and fermentation processes using such a yeast. The yeast has an exogenous invertase gene and has a deletion or disruption of the PDC activity gene. Accordingly, the yeast is useful for manufacturing fermentation products other than ethanol from fermentation substrates containing sucrose.

1 - 25 . (canceled) 
     
     
         26 . A process for manufacturing a fermentation product comprising: fermenting a substrate using a yeast, wherein the substrate comprises sucrose and the yeast comprises an exogenous invertase gene. 
     
     
         27 . The process of  claim 26 , wherein the yeast is a yeast of the  Issatchenkia orientalis/P. fermentans  clade. 
     
     
         28 . The process of  claim 27 , wherein the yeast is  Issatchenkia orientalis.    
     
     
         29 . The process of  claim 26 , wherein the yeast is PDC-negative. 
     
     
         30 . The process of  claim 26 , wherein the process is microaerobic. 
     
     
         31 . The process of  claim 26 , wherein the volumetric oxygen uptake rate (OUR) is 0.5 to 40 mmol O 2 /(L·h). 
     
     
         32 - 34 . (canceled) 
     
     
         35 . The process of  claim 26 , wherein the specific OUR is 0.2 to 13 mmol O 2/ (g cell dry weight·h). 
     
     
         36 - 47 . (canceled) 
     
     
         48 . The process of  claim 26 , wherein the fermentation substrate comprises sucrose and glucose. 
     
     
         49 . The process of  claim 26 , wherein the fermentation substrate comprises sucrose and hydrozylates of starch. 
     
     
         50 . The process of  claim 26 , wherein the fermentation substrate comprises sucrose and xylose. 
     
     
         51 . The process of  claim 26 , wherein the fermentation substrate comprises sucrose and lignocellulosic hydrozylates. 
     
     
         52 . The process of  claim 26 , wherein the fermentation substrate comprises sucrose, glucose, and xylose. 
     
     
         53 . The process of  claim 26 , wherein the process has a ratio of invertase activity to glucose consumption rate of less than 95. 
     
     
         54 - 55 . (canceled) 
     
     
         56 . The process of  claim 26 , wherein the process has a ratio of invertase activity to glucose consumption rate of at least 0.95. 
     
     
         57 . (canceled) 
     
     
         58 . The process of  claim 26 , wherein the fermentation yield is at least 55 percent. 
     
     
         59 - 61 . (canceled) 
     
     
         62 . The process of  claim 26 , wherein the final titer is at least 30 g/liter. 
     
     
         63 . The process of  claim 26 , wherein the final titer is at least 80 g/liter. 
     
     
         64 . (canceled) 
     
     
         65 . The process of  claim 26 , wherein the fermentation product is selected from the group consisting of: lactic acid, citric acid, malonic acid, hydroxy butyric acid, adipic acid, lysine, keto-glutaric acid, glutaric acid, 3-hydroxy-proprionic acid, succinic acid, malic acid, fumaric acid, itaconic acid, muconic acid, methacrylic acid, and acetic acid and derivatives thereof and salts thereof. 
     
     
         66 - 68 . (canceled) 
     
     
         69 . The process of  claim 26 , wherein the invertase activity is in the range of about 2.5 to 50 (g glucose released/(g CDW*h)). 
     
     
         70 . The process of  claim 26 , wherein the ratio of invertase activity to glucose consumption rate (or glucose capacity) is in the range of about 0.5 to 25. 
     
     
         71 . (canceled)