Enzyme preparations yielding a clean taste

Abstract

The present invention describes a intracellular produced lactase, which comprises less than 40 units arylsulfatase activity per NLU of lactase activity. The invention also provides a process comprising treating a substrate with an enzyme preparation, wherein the enzyme preparation is substantially free from arylsulfatase.

1 . A process for producing a lactase comprising
 (a) producing an arylsulfatase deficient  Bacillus licheniformis  host cell using mutagenesis or recombinant genetic engineering to decrease the expression of a native arylsulfatase expression in the yeast or fungal host cell, wherein the arylsulfatase deficient host cell expresses less arylsulfatase than a parent yeast or fungal host cell not subjected to the mutagenesis or recombinant genetic engineering when cultured under the same conditions;   (b) isolating the arylsulfatase deficient yeast or fungal host cell;   (c) cultivating the arylsulfatase deficient yeast or fungal host cell in a nutrient medium under conditions resulting in expression of a lactase polypeptide; and   (d) recovering the lactase polypeptide from the nutrient medium or from the yeast or fungal host cell.   
     
     
         2 . The process according to  claim 1 , wherein the mutagenesis is random mutagenesis. 
     
     
         3 . The process according to  claim 2 , wherein the random mutagenesis is physical or chemical mutagenesis. 
     
     
         4 . The process according to  claim 1 , wherein the recombinant genetic engineering is one-step gene disruption, marker insertion, site-directed mutagenesis or deletion. 
     
     
         5 . The process according to  claim 1 , wherein  Bacillus licheniformis  host cell is transformed with a nucleotide encoding a lactase following step (a) or step (b). 
     
     
         6 . The lactase obtained by the process of  claim 1 , which comprises less than 40 units arylsulfatase activity per NLU of lactase activity. 
     
     
         7 . The lactase according to  claim 6 , which is an intracellular lactase. 
     
     
         8 . The lactase according to  claim 6 , which is a neutral lactase. 
     
     
         9 . The lactase according to  claim 6 , which has a pH optimum of between 6.0 and 8.0. 
     
     
         10 . The lactase according to  claim 1 , which has less than 0.5 RFU/min protease activity per NLU of lactase activity. 
     
     
         11 . A dairy product comprising the lactase according to  claim 6 . 
     
     
         12 . The dairy product according to  claim 11  which is a fermented milk product. 
     
     
         13 . The dairy product according to  claim 12 , wherein the level of arylsulfatase in the dairy product is at most 500*10E3 arylsulfatase units per liter of dairy product.