Xylitol producing metschnikowia species

Abstract

Provided herein are Metschnikowia species that produce xylitol from xylose when cultured, as well as methods to make and use these Metschnikowia species.

We claim: 
     
         1 . An isolated  Metschnikowia  species comprising: (a) at least one exogenous nucleic acid encoding a xylose reductase or that results in overexpression of a xylose reductase of the isolated  Metschnikowia  species; and (b) a genetic modification that attenuates or inactivates a xylitol dehydrogenase of the isolated  Metschnikowia  species, wherein the isolated  Metschnikowia  species: (i) is the  Metschnikowia  species designated Accession No. 081116-01, deposited at the International Depositary Authority of Canada, an International Depositary Authority, on Nov. 8, 2016, under the terms of the Budapest Treaty, and (ii) produces at least 0.50 g/L/h of xylitol from xylose when cultured. 
     
     
         2 . The isolated  Metschnikowia  species of  claim 1 , wherein the isolated  Metschnikowia  species produces at least 5.00 g/L/h of xylitol from xylose when cultured. 
     
     
         3 . The isolated  Metschnikowia  species of  claim 1 , wherein the isolated  Metschnikowia  species produces at least 200 g/L of xylitol from xylose when cultured. 
     
     
         4 . (canceled) 
     
     
         5 . The isolated  Metschnikowia  species of  claim 1 , wherein the isolated  Metschnikowia  species comprises one or more mutations from adaptive evolution. 
     
     
         6 . The isolated  Metschnikowia  species of  claim 1 , wherein the at least one exogenous nucleic acid encoding a xylose reductase is a heterologous nucleic acid. 
     
     
         7 . (canceled) 
     
     
         8 . The isolated  Metschnikowia  species of  claim 1 , wherein the xylose reductase comprises the amino acid sequence of SEQ ID NO: 11 or an amino acid sequence with at least 95% sequence identity to SEQ ID NO: 11. 
     
     
         9 . The isolated  Metschnikowia  species of  claim 1 , wherein the genetic modification comprises the deletion of at least one allele encoding the xylitol dehydrogenase or a portion thereof of the isolated  Metschnikowia  species. 
     
     
         10 . The isolated  Metschnikowia  species of  claim 1 , wherein the genetic modification comprises the deletion of both alleles encoding the xylitol dehydrogenase or a portion thereof of the isolated  Metschnikowia  species. 
     
     
         11 . The isolated  Metschnikowia  species of  claim 1 ,wherein the isolated  Metschnikowia  species comprises multiple copies of the exogenous nucleic acid encoding the xylose reductase. 
     
     
         12 . The isolated  Metschnikowia  species of  claim 11 , wherein the isolated  Metschnikowia  species comprises two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, fifteen, sixteen, seventeen, eighteen, nineteen, twenty, or more copies of the exogenous nucleic acid encoding the xylose reductase. 
     
     
         13 . (canceled) 
     
     
         14 . A method for producing xylitol comprising culturing the isolated  Metschnikowia  species of  claim 1  under conditions and for a sufficient period of time to produce xylitol from xylose. 
     
     
         15 . The method of  claim 14 , wherein the conditions comprise culturing the isolated  Metschnikowia  species in medium comprising xylose and a C3 carbon source, a C4 carbon source, a C5 carbon source, a C6 carbon source, or a combination thereof. 
     
     
         16 . The method of  claim 14 , wherein the conditions comprise culturing the isolated  Metschnikowia  species in medium comprising xylose and a co-substrate. 
     
     
         17 . The method of  claim 16 , wherein the co-substrate is glucose. 
     
     
         18 . The method of  claim 17 , wherein the medium is a xylose-rich medium comprising a glucose to xylose ratio of about 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10. 
     
     
         19 . (canceled) 
     
     
         20 . (canceled) 
     
     
         21 . (canceled) 
     
     
         22 . (canceled) 
     
     
         23 . (canceled) 
     
     
         24 . (canceled) 
     
     
         25 . Bioderived xylitol produced by the method of  claim 14 . 
     
     
         26 . A composition comprising the isolated  Metschnikowia  species of  claim 1  . 
     
     
         27 . (canceled) 
     
     
         28 . (canceled) 
     
     
         29 . (canceled) 
     
     
         30 . (canceled) 
     
     
         31 . (canceled)