The invention relates to a process for the production of ethanol, the process comprising fermenting of a carbon source composition with a recombinant yeast,

wherein the carbon source composition comprises at least glucose and arabinose; and
wherein the recombinant yeast comprises arabinose isomerase activity, ribulokinase activity, ribulose phosphate epimerase activity, glycerol uptake activity and glycerol conversion capacity; and
wherein the recombinant yeast further comprises a genetic modification leading to the reduction, downregulation, inhibition and/or elimination of the activity of a homologous protein with glycerol-efflux activity; and
wherein each of the glucose and the arabinose is converted into ethanol.

In addition, the invention relates to a recombinant yeast that can be used in such a process.

The present disclosure relates to an enzyme complex of arabinose isomerase, agarase and 3,6-anhydro galactosidase and a method for producing tagatose by degrading agar using the same. By using the enzyme complex according to the present disclosure, agar obtained from marine biomass can be degraded effectively and useful physiologically active substances such as tagatose can be obtained effectively therefrom.

The invention relates to a method for preparing a yeast which is capable of simultaneously fermenting a pentose and a hexose sugar, the method comprising providing a yeast which comprises: one or more heterologous genes encoding an enzyme of a pentose metabolic pathway, a disruption of a gene encoding a ribulose-phosphate 3-epimerase and a disruption of a gene encoding a glucose-6-phosphate isomerase, and one or more overexpressed endogenous genes encoding an enzyme of the pentose phosphate pathway; and subjecting the 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 when grown on a media comprising a hexose and at least one pentose sugar, so as to obtain an evolved yeast.

The present invention relates to a temperature optimized L-arabinose isomerase with a high catalytic activity within feedstocks comprising a high concentration of divalent metal ions, a nucleic acid sequence encoding the inventive L-arabinose isomerase, a vector comprising the nucleic acid sequence encoding the inventive L-arabinose isomerase, a composition containing the inventive L-arabinose isomerase, a yeast cell comprising the inventive L- arabinose isomerase, the use of the inventive L-arabinose isomerase, the composition or the yeast cell for the fermentation of feedstock with a high content of divalent metal ions.

Provided are excellent L-arabinose metabolic genes that function in yeasts. Provided is an L-arabinose metabolic gene cluster including an L-arabinose isomerase gene specified by a predetermined SEQ ID, an L-ribulokinase gene specified by a predetermined SEQ ID, and an L-ribulose-5-phosphate-4-epimerase gene specified by a predetermined SEQ ID.

Disclosed are components and methods for preparing tagatose from galactose via isomerization reactions using engineered components. The engineered components include microbial cells and methods for preparing microbial cells that have been engineered to catalyze isomerization of galactose to tagatose, in which the microbial cells express cytoplasmically an exogenous L-arabinose isomerase enzyme. The disclosed microbial cells may further be modified for use in methods for preparing tagatose from galactose via isomerization reactions where the microbial cells are treated with reagents that permeabilize the cells. The disclosed methods enable isomerization reactions of galactose to tagatose at relatively high rates, high conversions, and elevated temperatures.

The present disclosure relates to an enzyme complex of arabinose isomerase, agarase and 3,6-anhydro galactosidase and a method for producing tagatose by degrading agar using the same. By using the enzyme complex according to the present disclosure, agar obtained from marine biomass can be degraded effectively and useful physiologically active substances such as tagatose can be obtained effectively therefrom.

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.

The present invention relates to a recombinant strain having a modified sugar metabolic pathway resulting from the introduction of an enzyme derived from a different strain to a strain, and a high-speed screening method for various mutants and variants by which useful materials can be obtained or which can produce useful materials. The use of a recombinant vector and a strain according to the present invention not only can construct a new metabolic pathway in a strain to effectively obtain D-tagatose from D-galactose, but also can introduce randomly modified sugar isomerases and then allow D-galactose isomerase variants to be rapidly screened by conducting a cell growth-associated screening system.

The present invention relates to a new L-arabinose assimilation pathway and uses thereof. In particular, the present invention relates to polypeptides exhibiting L-arabinose isomerase, L-ribulokinase or L-ribulose-5-phosphate-4-epimerase activity, and recombinant host cells expressing said polypeptides. The present invention also relates to a method of producing a fermentation product, preferably ethanol, from an arabinose containing substrate, using a polypeptide or a host cell of the invention.