The present invention provides for a novel D-xylose isomerase (XI) gene that is suitable for metabolic engineering of Saccharomyces cerevisiae for an improved consumption of D-xylose.

This disclosure provides epimerase enzymes useful for commercial scale production of allulose from fructose. The disclosed enzymes (epimerase variants) are variants of Burkholderia multivorans CGD1 xylose isomerase engineered to have improved catalytic activity of about 1.5- to 2-fold compared with the parent enzyme.

The present invention provides for a nucleic acid encoding an isomerase and uses of the isomerase for bioconversion of sugar substrates. The invention represents an advancement in the field of enzyme engineering and discloses a modified nucleic acid for achieving optimum expression of a protein having isomerase activity in a heterologous host. The invention also discloses vectors carrying the modified nucleic acid and recombinant host cells carrying the vectors. The invention also discloses the process for producing a recombinant host cell, process for production of the recombinant enzyme and the process for bioconversion of sugars into their respective isomers using the recombinant protein.

Described herein are microorganisms, in particular yeast, which have been transformed with one or more expression construct(s) for i) the overexpression of the native genes encoding xylulose kinase (XKS1), transaldolase (TAL1), transketolase 1 (TKL1) and transketolase 2 (TKL2) and ii) the expression of a functional heterologous gene encoding a xylose isomerase (XI), where the xylose isomerase (XI) gene is derived from a microorganism selected from the group consisting of T. neapolitana, A. andensis and C. clariflavum. Also described herein are expression constructs, methods for fermenting pentose sugars using the microorganisms and methods for producing such microorganisms.

A method for preparing a yeast capable of simultaneously fermenting a pentose and a hexose sugar, comprising: (a) providing a yeast comprising: one or more heterologous genes encoding an enzyme of a pentose metabolic pathway; disruptions of a gene encoding a ribulose-phosphate 3-epimerase and of a gene encoding a glucose-6-phosphate isomerase; one or more overexpressed endogenous genes encoding an enzyme of the pentose phosphate pathway; and a disruption of one or more genes encoding an NADPH dependent 6-phosphogluconate dehydrogenase, (b) subjecting said yeast to evolutionary engineering on a medium comprising a hexose sugar and at least one pentose sugar, selecting for a yeast with improved growth rate obtain an evolved yeast; (d) restoring, in the evolved yeast, one or more of the disrupted genes, or: (d) identifying genetic permutations in at least part of the genome of the evolved yeast by genome sequencing; (e) constructing an improved pentose and hexose-fermenting yeast comprising one or more said genetic permutations. Also described is a recombinant yeast comprising one or more heterologous genes of a pentose metabolic pathway, and a gene encoding a variant of a parent polypeptide, the variant comprising an amino acid sequence comprising at least one mutation, when aligned with the amino acid sequence in SEQ ID NO: 6.

There is provided a method for treating or reducing the effects of fructose intolerance and health problems associated with excessive fructose intake by administration of glucose isomerase. Other embodiments are also disclosed.

The present invention relates to a genetically engineered yeast capable of manufacturing a fermentation product using sucrose as a fermentation substrate, and fermentation processes using such a yeast. The yeast has an exogenous invertase gene and has a deletion or disruption of the PDC activity gene. Accordingly, the yeast is useful for manufacturing fermentation products other than ethanol from fermentation substrates containing sucrose.

The invention is in the field of enzymology. More in particular, it provides a method for the isomerization of glucose into fructose wherein the glucose is derived from lignocellulosic material. More in particular, it provides a method for converting glucose into fructose comprising the steps of: providing a composition comprising water, glucose and lignin, enzymatically converting the glucose to fructose in the presence of a glucose isomerase, and optionally purifying the fructose from the solution, wherein the glucose isomerase comprises an amino acid sequence that is at least 90% identical with the sequence according to SEQ ID NO: 1 or SEQ ID NO: 2.

The invention is in the field of biotechnology and involves recombinant DNA technology. It provides means and methods for obtaining an insoluble active fusion protein comprising xylose isomerase activity. More in particular, the invention relates to a method for obtaining active insoluble xylose isomerase, comprising the expression in a host organism of a recombinant gene encoding a fusion protein comprising a xylose isomerase in combination with a PPIase, thereby obtaining the active insoluble xylose isomerase. It also provides recombinant fusion proteins comprising xylose isomerase activity as well as their use in converting xylose to xylulose and glucose to fructose.

Genetically engineered cells and methods are presented that enhance the consumption of xylose in a medium comprising a mix of five- and six-carbon sugars. Method of using these microbes to enhance xylose utilization and methods of making value products using these microbes are also disclosed herein.