The present disclosure concerns recombinant yeast host cells having a first genetic modification for downregulating a first metabolic pathway that converts NADP.sup.+ to NADPH, as well as a second genetic modification for upregulating a second metabolic pathway that converts NADP.sup.+ to NADPH. The second genetic modification allows the expression of a glyceraldehyde-3-phosphate dehydrogenase lacking phosphorylating activity, which can, in some embodiments, be from enzyme commission 1.2.1.9 or 1.2.1.90. The second pathway is distinct from the first metabolic pathway. The present disclosure also concerns a process for making and improving the yield of a fermented product, such as ethanol, using the recombinant yeast host cell.

The present invention relates to methods of producing a sugar reduced product from biomass comprising treating the biomass with fermentation enzymes. In an embodiment, treating with fermentation enzymes comprises fermentation. The present invention also relates to sugar reduced products produced by such methods and methods of producing fermentation enzymes.

A method for preparing a nitrogen-containing heterocyclic compound and a derivative thereof by an enzymatic-chemical cascade method, comprising: reacting an alcohol, an amine, an alcohol dehydrogenase, a flavin molecule and a coenzyme in a solvent to obtain the nitrogen-containing heterocyclic compound and the derivative thereof; compared with the prior art, the method is a green and economical enzymatic-chemical cascade method, and is used for synthesizing nitrogen-containing heterocyclic compounds and derivatives thereof; compared with a common toxic chemical catalyst, the alcohol dehydrogenase is selected as a catalyst in the method, which has the characteristics of high substrate specificity, no pollution, high catalytic efficiency, no toxic solvents and simple post-treatment.

A method for preparing a nitrogen-containing heterocyclic compound and a derivative thereof by an enzymatic-chemical cascade method, comprising: reacting an alcohol, an amine, an alcohol dehydrogenase, a flavin molecule and a coenzyme in a solvent to obtain the nitrogen-containing heterocyclic compound and the derivative thereof; compared with the prior art, the method is a green and economical enzymatic-chemical cascade method, and is used for synthesizing nitrogen-containing heterocyclic compounds and derivatives thereof; compared with a common toxic chemical catalyst, the alcohol dehydrogenase is selected as a catalyst in the method, which has the characteristics of high substrate specificity, no pollution, high catalytic efficiency, no toxic solvents and simple post-treatment.

A method for obtaining psicose from a mixture of fructose and psicose includes adding a mannitol dehydrogenase to a mixture of fructose and psicose to convert fructose into mannitol, and separating the mannitol from the psicose. Accordingly, the psicose can be more easily isolated from the mannitol with high efficiency by using the method.

A method for obtaining psicose from a mixture of fructose and psicose includes adding a mannitol dehydrogenase to a mixture of fructose and psicose to convert fructose into mannitol, and separating the mannitol from the psicose. Accordingly, the psicose can be more easily isolated from the mannitol with high efficiency by using the method.