Trichoderma reesei host cells expressing a glucoamylase from aspergillus fumigatus and methods of use thereof

Abstract

Fungal glucoamylases from Aspergillus fumigatus —expressed in Trichoderma reesei host cells (AfGATR) are provided. Trichoderma reesei host cells express AfGATRs at higher, or at least comparable, levels to natively expressed AfGA Aspergillus fumigatus . AfGATRs, including AfGA1TR and AfGA2TR, exhibit high activity at elevated temperatures and at low pH, so AfGATRs can be used efficiently in a process of saccharification in the presence of alpha-amylase, such as Aspergillus kawachii alpha-amylase (AkAA). AfGATRs advantageously catalyze starch saccharification to an oligosaccharide composition significantly enriched in DP1 (i.e., glucose) compared to the products of saccharification catalyzed by Aspergillus niger glucoamylase (AnGA) or native AfGA expressed in Aspergillus fumigatus . AfGATRs such as AfGA1TR, AfGA2TR or a variant thereof can be used at a lower dosage than AnGA and natively expressed AfGAs to produce comparable levels of glucose.

1 - 29 . (canceled) 
     
     
         30 . A yeast cell that expresses AfGA or variant thereof, wherein the AfGA or variant thereof comprises an amino acid sequence with at least 90% sequence identity to the sequence of SEQ ID NO: 12 or 13. 
     
     
         31 . The yeast cell according to  claim 30 , wherein the yeast cell secretes the AfGA. 
     
     
         32 . The yeast cell according to  claim 30 , wherein the AfGA or variant thereof comprises an amino acid sequence with at least 95% or 99% sequence identity to the sequence of SEQ ID NO: 12 or 13. 
     
     
         33 . The yeast cell according to  claim 32 , wherein the AfGA comprises the sequence of SEQ ID NO: 12 or 13. 
     
     
         34 . The yeast cell according to  claim 30 , wherein the yeast cell further expresses an additional glucoamylase. 
     
     
         35 . Use of a yeast cell that expresses AfGA or variant thereof, in a simultaneous saccharification and fermentation (SSF) process, wherein the AfGA or variant thereof comprises an amino acid sequence with at least 80% sequence identity to SEQ ID NO: 12 or 13, and wherein the yeast cell and the AfGA or variant thereof are present in the same process step. 
     
     
         36 . The use according to  claim 35 , wherein the AfGA or variant thereof comprises an amino acid sequence with at least 95% or 99% sequence identity to the sequence of SEQ ID NO: 12 or 13 
     
     
         37 . The use according to  claim 35 , wherein the yeast cell expresses an additional glucoamylase. 
     
     
         38 . The use according to  claim 35 , wherein the use comprises the production of ethanol. 
     
     
         39 . The use according to  claim 38 , further comprising the purification and recovery of ethanol.