Process for the production of cellulolytic and/or hemicellulolytic enzymes
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
(a) growing the microorganism in a culture medium in the presence of a source of carbon;
(b) inducing the production of the enzymes by the microorganism in the presence of an inducing substrate, wherein said inducing substrate is a mixture of cellulosic hydrolysates, lactose and a solution of hemicellulosic hydrolysates, the quantities of each of the constituents of the mixture are defined by the following limits:
50% to 65% by weight of cellulosic hydrolysates;
22% to 24% by weight of lactose; and
15% to 25% by weight of a solution of hemicellulosic hydrolysates;
the sum of these three constituents being equal to 100%, and wherein the microorganism belongs to the species Trichoderma reesei which is deleted for catabolic repression by glucose,
wherein the inducing substrate is supplied in a solution having a concentration of 350 to 600 g/L, and
wherein both the source of carbon and the inducing substrate comprise sugar, and wherein the cellulosic hydrolysates and the solution of hemicellulosic hydrolysates are obtained from a pretreatment of lignocellulosic biomass, and/or the cellulosic hydrolysates are obtained directly from a process for the transformation of lignocellulosic biomass into ethanol.
2. The process according to claim 1 , wherein the inducing substrate is supplied in a solution having a concentration in the range of 450 to 550 g/L.
3. The process of claim 1 , wherein the inducing substrate is a mixture of 60% by weight of cellulosic hydrolysates, 23% by weight of lactose and 17% by weight of a solution of hemicellulosic hydrolysates.
4. The process of claim 1 , wherein the carbon source in (a) is 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 derived from pre-treatment of a cellulosic biomass.
5. The process of claim 1 , wherein growth step (a) is conducted at a pH of 3.5 to 6 and the temperature is 20° C. to 35° C.
6. The process of claim 1 , wherein in (b) the induction solution is introduced at a flow rate of 30 to 45 mg per gram of cells per hour.
7. The process according to claim 1 , wherein the residual concentration of sugar in the culture medium during the production phase is less than 1 g/L.
8. The process of claim 1 , wherein the residual concentration of sugar in the culture medium during induction step (b) is less than 0.5 g/L.
9. The process of claim 1 , wherein the residual concentration of sugar in the culture medium during induction step (b) is less than 0.1 g/L.
10. The process of claim 1 , wherein the constituent of the inducing substrate that is 15% to 25% by weight of a solution of hemicellulosic hydrolysates consists essentially of xylose.
11. The process of claim 1 , wherein the production step is performed in a fed-batch reactor.
12. The process of claim 1 , wherein the cellulosic and/or hemicellulosic hydrolysate inducers are obtained from lignocellulosic biomass and are concentrated prior to addition to step (b).
13. The process of claim 1 , wherein the cellulosic hydrolysates comprise glucose.
14. The process of claim 1 , wherein a specific beta glucosidase activity of at least 1.2 IU/mg is achieved.
15. A process for the production of cellulolytic and/or hemicellulolytic enzymes by a cellulolytic and/or hemicellulolytic microorganism, comprising
(a) growing the microorganism in a culture medium in the presence of a source of carbon;
(b) inducing the production of the enzymes by the microorganism in the presence of an inducing substrate, wherein said inducing substrate is a mixture of cellulosic hydrolysates, lactose and a solution of hemicellulosic hydrolysates,
wherein
the cellulosic hydrolysates and the hemicellulosic hydrolysates are obtained from a pre-treatment of lignocellulosic biomass, and/or
the cellulosic hydrolysates are obtained directly from a process for the transformation of lignocellulosic biomass into ethanol,
wherein the quantities of each of the constituents of the mixture are defined by the following limits:
50% to 65% by weight of cellulosic hydrolysates;
22% to 24% by weight of lactose; and
15% to 25% by weight of a solution of hemicellulosic hydrolysates;
the sum of these three constituents being equal to 100%,
wherein
the microorganism belongs to the species Trichoderma reesei which is deleted for catabolic repression by glucose,
the cellulosic and/or hemicellulosic hydrolysate inducers obtained from lignocellulosic biomass are concentrated prior to addition to step (b), whereby the inducing substrate is supplied in a solution having a concentration of 350 to 600 g/L, and
both the source of carbon and the inducing substrate comprise sugar, whereby a specific beta glucosidase activity of at least 1.2 IU/mg is achieved.