Recombinant yeast expressing heterologous stl1 protein

Abstract

The present invention provides for novel metabolic pathways to reduce or modulate glycerol production and increase product formation. More specifically, the invention provides for a recombinant microorganism comprising one or more native and/or heterologous proteins that function to import glycerol and one or more native and/or heterologous enzymes that function in one or more engineered metabolic pathways to convert a carbohydrate source, such as lignocellulose, to a product, such as ethanol, wherein the one or more native and/or heterologous proteins or enzymes is activated, upregulated, or downregulated. The invention also provides for a recombinant microorganism comprising one or more native or heterologous proteins that function to regulate glycerol synthesis and one or more native and/or heterologous enzymes that function in one or more engineered metabolic pathways to convert a carbohydrate source to ethanol, wherein said one or more native and/or heterologous proteins or enzymes is activated, upregulated or downregulated. Also provided are methods for increasing cellular glycerol uptake and increasing recombinant production of fuels and other chemicals using the recombinant microorganisms of the invention.

What is claimed is: 
     
         1 . A recombinant yeast comprising a heterologous STL1 having at least 80% identity with the amino acid sequence of SEQ ID NO: 10. 
     
     
         2 . The recombinant yeast of  claim 1 , wherein the heterologous STL1 is under the transcriptional control of one or more heterologous promoters. 
     
     
         3 . The recombinant yeast of  claim 2 , wherein the one or more heterologous promoters comprise a TEF2 promoter and/or a ADH1 promoter. 
     
     
         4 . The recombinant yeast of  claim 1 , wherein the recombinant yeast further comprises a deletion or downregulation of one or more native enzymes that function to produce glycerol and/or regulate glycerol synthesis. 
     
     
         5 . The recombinant yeast of  claim 4 , wherein the one or more native enzymes that function to produce glycerol is GPP1, GPP2, GPD1 or GPD2. 
     
     
         6 . The recombinant yeast of  claim 1 , further comprising one or more heterologous saccharolytic enzymes. 
     
     
         7 . The recombinant yeast of  claim 6 , wherein the one or more heterologous enzymes comprise an alpha-amylase and/or a glucoamylase. 
     
     
         8 . The recombinant yeast of  claim 1 , wherein the heterologous STL1 reduces glycerol formation by more than about 5% of the glycerol produced by a control yeast without the heterologous STL1. 
     
     
         9 . The recombinant yeast of  claim 1  being from Saccharomyces sp. or Saccharomyces cerevisiae. 
     
     
         10 . The recombinant yeast of  claim 1  comprising a heterologous nucleic acid molecule encoding the heterologous STL1, wherein the heterologous nucleic acid molecule has at least 80% identity with the nucleic acid sequence of SEQ ID NO: 9. 
     
     
         11 . The recombinant yeast of  claim 1 , wherein the heterologous STL1 has at least 90% identity with the amino acid sequence of SEQ ID NO: 10. 
     
     
         12 . The recombinant yeast of  claim 1 , wherein the heterologous STL1 has at least 95% identity with the amino acid sequence of SEQ ID NO: 10. 
     
     
         13 . The recombinant yeast of  claim 1 , wherein the heterologous STL1 has at least 99% identity with the amino acid sequence of SEQ ID NO: 10. 
     
     
         14 . A process for converting biomass to ethanol comprising contacting biomass with a recombinant yeast according to  claim 1 . 
     
     
         15 . The process of  claim 14 , wherein the biomass comprises starch, sugar, and/or a lignocellulosic material. 
     
     
         16 . The process of  claim 16 , wherein the starch is derived from a corn mash. 
     
     
         17 . The process of  claim 14 , wherein the recombinant yeast comprises a heterologous nucleic acid molecule encoding the heterologous STL1, wherein the heterologous nucleic acid molecule has at least 80% identity with the nucleic acid sequence of SEQ ID NO: 9.