# US 2016/0257979 A1 · Methods for reducing contamination during enzymatic hydrolysis of biomass-derived cellulose

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- Number: US 2016/0257979 A1
- Document ID: US20160257979A1
- Status: Published application
- Kind: A1
- Application number: 15/062,155
- Filed: 2016-03-06
- Published: 2016-09-08
- Earliest claimed: 2015-03-06
- Assignees: API Intellectual Property Holdings, LLC
- Applicants: API Intellectual Property Holdings, LLC
- Inventors: Theodora RETSINA; Gonçalo PEREIRA; Vesa PYLKKANEN
- Web page: https://patentgrep.com/patent/US20160257979A1

## CPC

- C12P 19/02: Monosaccharides (2-ketogulonic acid C12P7/60)
- C12P 7/10: substrate containing cellulosic material
- C12P 19/14: produced by the action of a carbohydrase {(EC 3.2.x)}, e.g. by alpha-amylase {, e.g. by cellulase, hemicellulase}
- C12P 2201/00: Pretreatment of cellulosic or lignocellulosic material for subsequent enzymatic treatment or hydrolysis
- C12P 2203/00: Fermentation products obtained from optionally pretreated or hydrolyzed cellulosic or lignocellulosic material as the carbon source
- Y02E 50/10: Biofuels, e.g. bio-diesel
- C12P: FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE {(brewing of beer C12C; producing vinegar C12J; producing specific peptides or proteins C07K; producing enzymes C12N9/00; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification C12N15/00; measuring or testing processes involving enzymes or microorganisms C12Q; measuring or testing processes involving nucleic acid amplification reactions C12Q1/6844; fermentation processes to form a food composition, A21 or A23; compounds in general, see the relevant compound class, e.g. C01, C07)}
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

Some variations provide a method of enzymatically converting biomass-derived cellulose to glucose, comprising exposing the biomass-derived cellulose to (i) cellulase enzymes, to hydrolyze the cellulose to glucose; and (ii) an external sulfur-containing compound, to deter bacterial and/or yeast contamination during cellulose hydrolysis. In some embodiments, the sulfur-containing compound includes sulfur dioxide or lignosulfonates. When the sulfur-containing compound includes lignosulfonates, the lignosulfonates may also function as an enzyme surfactant to assist hydrolysis, in addition to deterring bacterial and/or yeast growth/contamination. This method may be applied to cellulose-rich solids obtained from the AVAP® fractionation process, the Green Power+® pretreatment process, or any other source of cellulose-rich solids.

## Claims

### Claim 1

A method of enzymatically converting biomass-derived cellulose to glucose, said method comprising exposing said biomass-derived cellulose to (i) cellulase enzymes, to hydrolyze said cellulose to glucose; and (ii) an external sulfur-containing compound, to deter bacterial and/or yeast contamination during cellulose hydrolysis.

### Claim 2 (depends on 1)

The method of claim 1, wherein said sulfur-containing compound includes sulfur dioxide.

### Claim 3 (depends on 1)

The method of claim 1, wherein said sulfur-containing compound includes lignosulfonates.

### Claim 4 (depends on 3)

The method of claim 3, wherein said lignosulfonates also function as an enzyme surfactant to assist hydrolysis.

### Claim 5 (depends on 1)

The method of claim 1, wherein said biomass-derived cellulose is obtained from biomass fractionation in the presence of sulfur dioxide, and wherein said sulfur dioxide, or a derivative thereof, is employed as said sulfur-containing compound during said cellulose hydrolysis.

### Claim 6 (depends on 5)

The method of claim 5, wherein lignosulfonic acid is employed as said sulfur-containing compound during said cellulose hydrolysis, wherein said lignosulfonic acid is produced by reaction between said sulfur dioxide and lignin contained in the same biomass from which biomass-derived cellulose is derived.

### Claim 7 (depends on 1)

The method of claim 1, wherein said sulfur-containing compound is present in solution during said cellulose hydrolysis at a concentration from about 10 ppm to about 1 wt %.

### Claim 8 (depends on 7)

The method of claim 7, wherein said sulfur-containing compound is present in solution during said cellulose hydrolysis at a concentration from about 10 ppm to about 1000 ppm.

### Claim 9 (depends on 1)

The method of claim 1, said method further comprising fermenting said glucose to a fermentation product.

### Claim 10 (depends on 9)

The method of claim 9, wherein said sulfur-containing compound is removed prior to said fermenting.

### Claim 11 (depends on 9)

The method of claim 9, wherein said sulfur-containing compound is removed following said fermenting.

### Claim 12

A process for producing a fermentation product from cellulosic biomass, said process comprising:
(a) in a digestor, fractionating a feedstock comprising lignocellulosic biomass in the presence of a solvent for lignin, a hydrolysis catalyst, and water, to produce a liquor containing hemicellulose, cellulose-rich solids, and lignin;
(b) substantially separating said cellulose-rich solids from said liquor;
(c) hydrolyzing said hemicellulose contained in said liquor to produce fermentable hemicellulosic monomers;
(d) enzymatically converting cellulose-rich solids to glucose, comprising exposing said cellulose-rich solids to (i) cellulase enzymes, to hydrolyze cellulose to glucose; and (ii) an external sulfur-containing compound, to deter bacterial and/or yeast contamination during cellulose hydrolysis; and
(e) fermenting at least a portion of said glucose and optionally said fermentable hemicellulosic monomers to a fermentation product.

### Claim 13 (depends on 12)

The process of claim 12, wherein said solvent for lignin comprises an oxygenated hydrocarbon, C1-C8 aliphatic or aromatic alcohol, aliphatic or aromatic hydrocarbon, organic acid, inorganic acid, ionic liquid, or combination thereof.

### Claim 14 (depends on 12)

The process of claim 12, wherein said hydrolysis catalyst in step (a) is selected from the group consisting of sulfur dioxide, sulfur trioxide, sulfurous acid, sulfuric acid, sulfonic acid, lignosulfonic acid, elemental sulfur, polysulfides, and combinations or derivatives thereof.

### Claim 15 (depends on 12)

The process of claim 12, wherein said sulfur-containing compound in step (d) is said hydrolysis catalyst from step (a), or a reaction product thereof.

### Claim 16 (depends on 15)

The process of claim 15, wherein said hydrolysis catalyst is sulfur dioxide and wherein said reaction product is lignosulfonic acid or lignosulfonate.

### Claim 17 (depends on 12)

The process of claim 12, wherein said fermentation product includes an organic acid selected from the group consisting of formic acid, acetic acid, oxalic acid, lactic acid, propionic acid, 3-hydroxypropionic acid, malonic acid, aspartic acid, fumaric acid, malic acid, succinic acid, glutaric acid, adipic acid, citric acid, itaconic acid, levulinic acid, ascorbic acid, gluconic acid, kojic acid, threonine, glutamic acid, proline, lysine, alanine, serine, and any isomers, derivatives, or combinations thereof.

### Claim 18 (depends on 12)

The process of claim 12, wherein said fermentation product includes an oxygenated compound selected from the group consisting of ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, glycerol, sorbitol, propanediol, butanediol, butanetriol, pentanediol, hexanediol, acetone, acetoin, butyrolactone, 3-hydroxybutyrolactone, and any isomers, derivatives, or combinations thereof.

### Claim 19 (depends on 12)

The process of claim 12, wherein said sulfur-containing compound is present in solution during said cellulose hydrolysis at a concentration from about 10 ppm to about 1 wt %.

### Claim 20 (depends on 19)

The method of claim 19, wherein said sulfur-containing compound is present in solution during said cellulose hydrolysis at a concentration from about 10 ppm to about 1000 ppm.