Cellulase production method based on the regulation of the dissolved oxygen pressure oscillation in the culture medium

• US 8,956,846 B2
• Filed: 03/24/2011
• Issued: 02/17/2015
• Est. Priority Date: 03/26/2010
• Status: Active Grant

• Current Assignee: IFP Energies Nouvelles
• Original Assignee: IFP Energies Nouvelles
• Inventors: Ben Chaabane, Fadhel, Cohen, Celine
• Primary Examiner(s): PROUTY, REBECCA E
• Application Number:
  US13/070,804
• Publication Number:
  US 20110236954A1
• Time in Patent Office: 1,426 Days
• Field of Search: None
• US Class Current: 435/209
• CPC Class Codes: C12N 1/14 Fungi culture of mushrooms A01G18/00; as new plants A01H15/00; Culture media therefor
• CPC Class Codes: C12N 9/2434 acting on beta-1,4-glucosidic bonds
• CPC Class Codes: C12N 9/2437 Cellulases (3.2.1.4; 3.2.1.74; 3.2.1.91; 3.2.1.150)
• CPC Class Codes: C12N 9/2477 Hemicellulases not provided in a preceding group
• CPC Class Codes: C12P 21/00 Preparation of peptides or proteins single cell protein C12N1/00

Abstract

The present invention relates to a method of producing cellulolytic and/or hemicellulolytic enzymes by a cellulolytic microorganism in a stirred and aerated bioreactor, comprising a growth stage in the presence of a carbon source and a production stage in the presence of a carbon-containing inductive substrate, wherein the supply of carbon-containing inductive substrate during the production stage is regulated by an oscillation of the dissolved oxygen partial pressure in the medium.

Claims

1. A method of producing cellulolytic and/or hemicellulolytic enzymes by a cellulolytic microorganism in a stirred and aerated bioreactor, comprising a growth stage in the presence of a carbon source and a production stage in the presence of a carbon-containing inductive substrate, wherein the supply of carbon-containing inductive substrate during the production stage is regulated according to the dissolved oxygen partial pressure in the growth medium, said pressure oscillating between two values Po_2min and Po_2max, the value of Po_2min being greater than the critical pressure PO_2critical below which the activity of the microorganism is affected and less than 95% of the saturation oxygen partial pressure Po_2sat set when starting the bioreactor, and the value of Po_2max being at least 5% greater than Po_2min, addition of the carbon-containing inductive substrate being started as soon as the dissolved oxygen partial pressure in the medium is greater than value Po_2max and stopped as soon as the dissolved oxygen pressure in the medium is below value Po2min.

2. A method as claimed in claim 1, wherein Po_2max ranges between 30 and 70% of Po_2sat and Po_2min ranges between 10 and 60% of Po2sat.

3. A method as claimed in claim 2, wherein _Po2max ranges between 40 and 60% of Po_2sat and Po_2min ranges between 30 and 50% of Po2sat.

4. A method as claimed in claim 1, wherein the carbon-containing inductive substrate is selected from among lactose, xylose, cellobiose, sophorose, residues obtained after ethanolic fermentation of the monomeric sugars of the enzymatic hydrolysates of cellulosic biomass and/or a crude extract of hydrosoluble pentoses from the pretreatment of a cellulosic biomass.

5. A method as claimed in claim 1, wherein the substrate is supplied in solution.

6. A method as claimed in claim 5, wherein the carbon-containing inductive substrate selected for the enzyme production stage is at a concentration of 10 to 800 g/L.

7. A method as claimed in claim 5, wherein the carbon-containing inductive substrate is a lactose solution.

8. A method as claimed in claim 1, wherein stifling and aeration of the bioreactor are set at a predetermined value allowing said bioreactor to have an oxygenation capacity corresponding to a Kla value ranging between 50 and 150 h⁻

1.

9. A method as claimed in claim 1, wherein the cellulolytic microorganism is selected from among fungi belonging to the Trichoderma, Aspergillus, Penicillium and Schizophyllum genera.

10. A method as claimed in claim 9, wherein the cellulolytic microorganism belongs to the Trichoderma reesei species.

11. The method of claim 5, wherein the carbon-containing inductive substrate selected for the enzyme production stage is at a concentration of 150 to 600 g/L.

12. The method of claim 5, wherein the carbon-containing inductive substrate is a lactose solution at a concentration of 250 g/L.

13. The method of claim 1 wherein the method is performed in a batch process.