Method for producing cellulolytic and/or hemicellulolytic enzymes

Abstract

The process for the production of cellulolytic and/or hemicellulolytic enzymes by a cellulolytic and/or hemicellulolytic microorganism according to the present invention comprises at least one phase for growth in the presence of a source of carbon and at least one phase for production in the presence of an inducing substrate, in which said inducing substrate is a mixture comprising 40% to 65% by weight of glucose or cellulosic hydrolysates, 21% to 25% by weight of lactose and 10% to 39% by weight of xylose or a solution of a lignocellulosic hemicellulosic hydrolysate, the sum of these three constituents being equal to 100%.

1 . A process for the production of cellulolytic and/or hemicellulolytic enzymes by a cellulolytic and/or hemicellulolytic microorganism, comprising at least one phase for growth in the presence of a source of carbon and at least one phase for production in the presence of an inducing substrate, in which said inducing substrate is a mixture of glucose or cellulosic hydrolysates, lactose and xylose or a solution of hemicellulolytic hydrolysates, the quantities of each of the constituents of the mixture being defined by the following limits:
 40% to 65% by weight of glucose or cellulosic hydrolysates;   21% to 25% by weight of lactose; and   10% to 39% by weight of xylose or a solution of hemicellulosic hydrolysates;   
       the sum of these three constituents being equal to 100%. 
     
     
         2 . A process according to  claim 1 , in which the microorganism belongs to the species  Trichoderma reesei  and is deleted for catabolic repression by glucose. 
     
     
         3 . A process according to  claim 1 , in which the inducing substrate is supplied in solution, the concentration of inducing substrate in the supply solution used during the production phase being 350 to 600 g/L. 
     
     
         4 . A process according to  claim 3 , in which the concentration is in the range 450 to 550 g/L. 
     
     
         5 . A process according to  claim 1 , in which the mixture constituting the inducing substrate comprises 50% to 65% by weight of glucose or cellulosic hydrolysates, 22% to 24% by weight of lactose and 15% to 25% by weight of xylose or a solution of hemicellulosic hydrolysates, the sum of the constituents being equal to 100%. 
     
     
         6 . A process according to  claim 5 , in which the inducing substrate is a mixture constituted by 60% by weight of glucose or cellulosic hydrolysates, 23% by weight of lactose and 17% by weight of xylose or hemicellulosic hydrolysates. 
     
     
         7 . A process according to  claim 1 , in which the carbonaceous substrate used during the growth phase is selected from glucose, xylose, lactose, residues obtained after ethanolic fermentation of monomeric sugars of the enzymatic hydrolysates of cellulosic biomass and/or an unrefined extract of hydrosoluble pentoses possibly derived from the pre-treatment of a cellulosic biomass. 
     
     
         8 . A process according to  claim 1 , in which the pH is adjusted to between 3.5 and 6 and the temperature is in the range 20° C. to 35° C. 
     
     
         9 . A process according to  claim 1 , in which the flow rate for introduction of the supply solution is 30 to 45 mg per gram of cells per hour. 
     
     
         10 . A process according to  claim 1 , in which the residual concentration of sugar in the culture medium during the production phase is less than 1 g/L, preferably less than 0.5 g/L and highly preferably less than 0.1 g/L.