Yeast propagation simultaneous with saccharification
The invention relates to a method for propagating yeast, for use in the production of a fermentation product from lignocellulosic biomass, including the steps that consist of: a. providing a reactor; b. placing in contact in said reactor: a population of yeasts capable of metabolising pentoses and hexoses, with 0.2 to 2.0 g of yeast solids per kg of prepared complete medium, raw marc from the pretreatment of the lignocellulosic biomass, with a solids content (MS) of 8% to 15%, nutrients, and cellulases, with 5 to 15 mg of proteins per gram of MS; and c. incubating the mixture at a temperature of 25° C. to 38° C., preferably 28° C. to 33° C., in microaerobiosis, in which the saccharification of the raw marc and the growth of the yeast are carried out simultaneously.
1. A method for propagating yeasts, for use in the production of a fermentation product from lignocellulosic biomass, consisting of the steps of:
a. providing a reactor,
b. placing in contact in said reactor:
a population of yeasts capable of metabolizing pentoses and hexoses, in a proportion of from 0.2 to 2.0 g of yeast dry matter per kg of prepared complete medium, wherein the yeasts are from the yeast strain deposited with the CNCM on Jun. 26, 2013, under Accession Number I-4783,
raw marc obtained from pretreatment of the lignocellulosic biomass at a solid content (SC) of between 8% and 15%, wherein said pretreatment does not include extraction and/or enzymatic hydrolysis,
nutrients; and
cellulases in a proportion of from 5 to 15 mg of protein per gram of SC,
c. incubating the mixture at a temperature of between 25° C. and 38° C. in microaerobiosis,
wherein the saccharification of the raw marc and the growth of the yeasts are carried out simultaneously.
2. The propagating method as claimed in claim 1 , wherein the pentoses are xylose and/or arabinose.
3. The propagating method as claimed in claim 1 , wherein the hexose is glucose.
4. The propagating method as claimed in claim 1 , wherein the incubation in step c. is maintained until a cell concentration between 5.0×10 8 and 1.0×10 9 cells per millilitre is obtained.
5. The propagating method as claimed in claim 1 , wherein the yeasts are inoculated in a proportion of from 0.3 to 0.6 g/kg in the form of dry yeasts, the raw marc is used in a proportion of 10% of SC and the cellulases in a proportion of 7 mg of proteins per gram of SC, the aeration rate is set at 0.1 VVM, the temperature is set at 30° C. and the pH of the medium is set at pH 5.0.
6. The method according to claim 1 , wherein in step c., the temperature is between 28° C. and 33° C.
7. A method for producing a fermented product from a lignocellulosic biomass, consisting of the steps of sequentially:
a. pretreating the lignocellulosic biomass so as to obtain raw marc, wherein said pretreating step does not include extraction and/or enzymatic hydrolysis,
b. bringing a fraction of the raw pretreated marc, in a proportion of from 10% to 12% of solids (SC), into contact with (i) a population of yeasts capable of metabolizing pentoses and hexoses, wherein the yeasts are from the yeast strain deposited with the CNCM, on Jun. 26, 2013, under Accession Number I-4783, (ii) cellulases in a proportion of from 5 to 15 mg of protein per gram of SC, and (iii) optionally, nutrients,
c. incubating the mixture at a temperature of between 25° C. and 38° C. in microaerobiosis, so as to obtain propagated yeasts by simultaneous saccharification and propagation,
d. transferring all or part of the propagated yeasts for bringing into contact with the fermentation must comprising a pentose source and a hexose source,
e. carrying out the fermentation, under anaerobic or semi-aerobic conditions, and
f. obtaining the fermented product.
8. The method as claimed in claim 7 , wherein the lignocellulosic biomass is a biomass of plant origin.
9. The method as claimed in claim 7 , wherein the fermented product obtained is ethanol.
10. The method according to claim 7 , wherein in step c., the temperature is between 28° C. and 35° C.
11. The method according to claim 7 , wherein the incubation in step c. is maintained until a cell concentration between 5.0×10 8 and 1.0×10 9 cells per millilitre is obtained.