High gravity, fed-batch ionic liquid based process for deconstructing biomass
View Patent ↗In one aspect, the present invention provides methods for preparing a fermentation product. The methods include pre-treating a mixture of biomass and ionic liquid, wherein the ionic liquid comprises a choline cation and the biomass comprises polysaccharide and lignin. The methods further include forming hydrolysates from the introduction of glycoside hydrolase to the pre-treated mixture at conditions sufficient to produce a sugar composition mixture for fermentation steps. The present invention provides methods for loading biomass mixtures in a batch-fed process, wherein the biomass slurries can be loaded into water or a concentrated sugar composition for hydrolysate production. The methods can be performed in a one-pot process, wherein the ionic liquids are present in the mixtures throughout each step. Aspects of the invention provide compositions of sugar composition mixtures and fermentation product mixtures.
1. A method of producing a polysaccharide hydrolysate from biomass, the method comprising:
(i) providing a slurry comprising pre-treated biomass at a concentration of at least about 5% w/w and less than about 50% w/w, an ionic liquid or a mixture of ionic liquids at a concentration of between about 5% w/w and about 25% w/w, and water, wherein the ionic liquid or the mixture of ionic liquids and biomass are present in the pre-treated slurry at a mass ratio R m/i of from about 0.2 to about 5, and wherein the ionic liquid or the mixture of ionic liquids comprises:
a) a choline cation; and
b) an anion selected from the group consisting of a carboxylic acid anion, dicarboxylic acid anion, lysinate, hydroxide anion, bisulfate anion, dihydrogen phosphate anion, phosphate anion, bicarbonate anion, and chloride anion;
(ii) combining a portion of the pre-treated biomass slurry with a glycoside hydrolase and a hydrolysate seed batch comprising a sugar and water, wherein the sugar is at a concentration of at least 70% w/w in the hydrolysate seed batch; and
(iii) maintaining the mixture formed in step (ii) under conditions sufficient to hydrolyze the polysaccharide present in the portion of the pre-treated biomass slurry, thereby forming a mixture comprising a hydrolyzed polysaccharide;
wherein the biomass comprises polysaccharide and lignin, and
wherein at least 70% of glucan and/or xylan present in the biomass is converted into a monosaccharide.
2. The method of claim 1 , wherein the portion of the pretreated biomass slurry of step (ii) is introduced at a rate of from at least 2 grams per day to about 20 grams per day per 30 milliliters of the mixture comprising the glycoside hydrolase and hydrolysate seed batch.
3. The method of claim 1 , wherein the mixture of step (iii) is maintained under conditions sufficient to hydrolyze the polysaccharide for at least 1 day, or at least 2 days.
4. The method of claim 1 , further comprising:
(iv) adding to the mixture formed in step (iii) an additional portion of the pre-treated biomass slurry of step (i), and maintaining the mixture under conditions sufficient to hydrolyze the polysaccharide present in the additional portion of the pre-treated biomass slurry; and
(v) repeating the step of (iv) 1 to 100 times.
5. The method of claim 4 , wherein the additional portion of the pretreated biomass slurry of step (iv) is added at a rate of from at least 2 grams per day to about 20 grams per day per 30 milliliters of the mixture formed in step (iii).
6. The method of claim 5 , wherein the addition of the portion of the pre-treated biomass slurry of step (iv) is repeated for at least 4 days.
7. The method of claim 4 , wherein the mixture of step (iv) is maintained under conditions sufficient to hydrolyze the polysaccharide for at least 1 day, or at least 2 days.