Heterologous Alpha Amylase Expression in Aspergillus

Abstract

The present invention relates to the co-expression and production of a heterologous alpha amylase and an endogenous glucoamylase in an Aspergillus strain and enzyme compositions including the same.

1 . An  Aspergillus  fungal strain comprising DNA encoding a glucoamylase and DNA encoding a heterologous alpha amylase comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 3, wherein both the glucoamylase and the heterologous alpha amylase are expressed and secreted by the  Aspergillus  fungal strain. 
     
     
         2 . The  Aspergillus  strain of  claim 1 , wherein the strain is an  A. niger, A. nidulans, A. oryzae  or  A. awamori  strain. 
     
     
         3 . The  Aspergillus  strain of  claim 2 , wherein the  Aspergillus  strain is an  A. niger  strain. 
     
     
         4 . The  Aspergillus  strain of  claim 2 , wherein the secreted glucoamylase comprises at least 40% of the total amount of secreted protein from the strain. 
     
     
         5 . A culture medium comprising the  Aspergillus  strain of  claim 1 . 
     
     
         6 . An enzyme composition obtained from the culture medium of  claim 1 . 
     
     
         7 . An enzyme composition comprising the culture medium of  claim 6 . 
     
     
         8 . An  Aspergillus  strain comprising a) DNA encoding an endogenous glucoamylase and b) DNA encoding a heterologous alpha amylase having at least 95% sequence identity to SEQ ID NO: 3, wherein the  Aspergillus  strain expresses both the glucoamylase and the heterologous alpha amylase and overproduces the glucoamylase. 
     
     
         9 . A culture medium comprising the  Aspergillus  strain of  claim 8 . 
     
     
         10 . A method of producing an alpha amylase in an  Aspergillus  cell which comprises, culturing the  Aspergillus  fungal strain of  claim 1  under conditions suitable for the expression and production of the heterologous alpha amylase and producing the heterologous alpha amylase. 
     
     
         11 . The method according to  claim 10 , wherein the  Aspergillus  cell also expresses and produces glucoamylase. 
     
     
         12 . The method according to  claim 11 , wherein the  Aspergillus  is an  A. niger  strain. 
     
     
         13 . The method according to  claim 11  further comprising recovering the produced alpha amylase and glucoamylase. 
     
     
         14 . The method according to  claim 11 , wherein the  Aspergillus  strain is an overproducing glucoamylase strain. 
     
     
         15 . A method for producing an acid stable alpha amylase and a glucoamylase in a filamentous fungal host cell comprising
 a) obtaining the fungal strain of  claim 1 ,   b) cultivating the transformed host cell in a suitable culture medium to allow expression of the alpha amylase and the glucoamylase, and   c) producing the alpha amylase and the glucoamylase.   
     
     
         16 . The method according to  claim 15  further comprising recovering the produced glucoamylase and alpha amylase. 
     
     
         17 . The method according to  claim 15 , wherein the filamentous host cell is an  Aspergillus  strain. 
     
     
         18 . The method according to  claim 17 , wherein the  Aspergillus  strain is an  A. niger  strain. 
     
     
         19 . The method according to  claim 17 , wherein the secreted glucoamylase comprises at least 40% of the total amount of secreted protein from the strain. 
     
     
         20 . A method of hydrolyzing starch comprising contacting a substrate containing starch with the enzyme composition of  claim 6  under suitable conditions for starch hydrolysis and obtaining hydrolyzed starch. 
     
     
         21 . The method according to  claim 20 , wherein the starch is granular starch. 
     
     
         22 . The method according to  claim 21 , wherein the contacting is at a temperature below the gelatinization temperature of the granular starch in the substrate. 
     
     
         23 . The method according to  claim 20 , wherein the substrate is a grain or fractionated part thereof.