# US 7,745,177 B2 · Method for manufacturing xylitol with high-yield and high-productivity

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- Number: US 7,745,177 B2
- Document ID: US7745177B2
- Status: Granted
- Kind: B2
- Application number: 11/677,685
- Filed: 2007-02-22
- Published: 2008-08-28
- Granted: 2010-06-29
- Earliest claimed: 2007-02-22
- Assignees: Korea Advanced Institute of Science and Technology; LPBIO Co., Ltd.
- Inventors: Jung-Hoe Kim; Byoung-Sam Ko
- Web page: https://patentgrep.com/patent/US7745177B2

## CPC

- C12P 7/18: polyhydric
- 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)}

## Abstract

The present invention provides a method for manufacturing xylitol with high-yield and high-productivity by using a xylitol dehydrogenase-deficient mutant of xylitol producing microorganism. This goal is achieved through modification of the metabolic pathway of the xylitol producing microorganism, preferably a natural xylose-assimilating yeasts and fungi, by disrupting or inactivating the expression of desired genes.

## Claims

### Claim 1

A method for manufacturing xylitol which comprises a step of culturing a xylitol dehydrogenase-deficient mutant of Candida tropicalis whose xylitol dehydrogenase expression is disrupted by deletion, substitution or insertion into a part of the xylitol dehydrogenase coding sequence in a medium comprising xylose, a carbon source, a nitrogen source, and trace elements until the xylose contained in the medium is substantially consumed, whereby xylitol is produced.

### Claim 2 (depends on 1)

The method for manufacturing xylitol of claim 1 wherein the carbon source comprises glycerol, fructose, galactose, sucrose, mannose, maltose, cellobiose or a mixture thereof.

### Claim 3 (depends on 1)

The method for manufacturing xylitol of claim 1 wherein the nitrogen source comprises yeast extract.

### Claim 4 (depends on 1)

The method for manufacturing xylitol of claim 1 wherein the trace elements comprise potassium dihydrogenphosphate, magnesium sulfate heptahydrate or a mixture thereof.

### Claim 5 (depends on 1)

The method for manufacturing xylitol of claim 1 wherein the xylitol dehydrogenase-deficient mutant is cultured at 20° C. to 40° C.

### Claim 6 (depends on 1)

The method for manufacturing xylitol of claim 1 wherein the xylitol dehydrogenase-deficient mutant is cultured in a fed-batch under a condition of agitation speed 300 to 500 rpm and oxygen transfer rate (OTR) 10 mmol O2 l−1 h−1 to 42 mmol O2 l−1 h−1.

### Claim 7 (depends on 1)

The method for manufacturing xylitol of claim 1 wherein the xylose is added to the medium in a form of hydrolysate of corncob.