Provided are a Bacillus subtilis genetically engineered bacterium for producing tagatose and a method for preparing tagatose. The genetically engineered bacterium comprises constructing thermostable ?-glucan phosphorylases, thermostable glucose phosphomutases, thermostable glucose phosphate isomerases, thermostable 6-tagatose phosphate epimerases, and thermostable 6-tagatose phosphate phosphatases which are independently expressed or co-expressed. The usage of the genetically engineered bacterium can effectively convert starch into tagatose. Compared with existing methods for producing tagatose, the method has advantages such as suitability for whole-cell recycling, high safety, high yield, simple production process, low cost, and easiness in large-scale preparation.

Provided is a recombinant microorganism for producing carnosine, histidine and beta-alanine and a method for producing carnosine, histidine and beta-alanine by using same and, more particularly, to: a recombinant microorganism for high production of carnosine, histidine and beta-alanine produced through the redesign of metabolic pathways; a method for producing same; and a method for producing carnosine, histidine and beta-alanine by using same. According to the present invention, in a microorganism capable of producing histidine and beta-alanine, by enhancing the pentose phosphate pathways through the replacement of a pentose phosphate pathway-related operon gene with a highly expressing synthetic promoter and the replacement of a pgi gene with an initiation codon, and inducing enhancement of the production of histidine and beta-alanine through the overexpression of genes on histidine and beta-alanine metabolic pathways, respectively, it is possible to develop a recombinant microorganism for high production of histidine and beta-alanine.

Provided herein, in some embodiments, are systems, methods, and compositions (e.g., cells and cell lysates) for enzymatically converting a polymeric glucose carbohydrate (e.g., starch) to sugar.

The invention relates to preparation of food ingredients enriched with a low-glycemic sugar replacement through enzymatic conversion. Food ingredients may be enriched with, for example, D-tagatose, D-allulose, D-allose, D-mannose, D-talose, and/or inositol by enzymatically converting saccharides found in flour, meal, ground tuber, ground pulse, ground bark, starch, malted grain or malt extract, maltodextrin, cellulose, cellodextrin, any of their derivatives (e.g., amylose, amylopectin, dextrin, cellobiose, etc.), and/or sucrose into D-tagatose, D-allulose, D-allose, D-mannose, D-talose and/or inositol. The enriched material can be used as a food ingredient instead of the low-glycemic sugar being purified for use as a food ingredient.

A method for preparing immobilized cells for producing mannose, and a method using same for producing mannose, comprising: fermenting to separately obtain fermentation broths of Escherichia coli or Bacillus subtilis expressing a-glucan phosphorylase, phosphoglucomutase, glucose phosphoisomerase, mannose-6-phosphate isomerase and mannose-6-phosphate phosphatase, and mixing the fermentation broths to obtain a mixed fermentation broth.

A method for preparing glucosamine includes the steps of converting fructose-6-phosphate (F6P) and an ammonium salt to glucosamine-6-phosphate (GlcN6P) under the catalysis of glucosamine-6-phosphate deaminase (EC 3.5.99.6, GlmD); and producing glucosamine (GlcN) by the dephosphorylation of GlcN6P under the catalysis of an enzyme capable of catalyzing the dephosphorylation. Such a method can be used to prepare glucosamine by in vitro enzymatic biosystem.

Provided herein, in some embodiments, are systems, methods, and compositions (e.g., cells and cell lysates) for enzymatically converting a polymeric glucose carbohydrate (e.g., starch) to sugar.

Provided is an engineered pathway that can function in a cell-free system, cellular system or a combination thereof to convert a sugar to a chemical or biofuel.

Disclosed herein are methods of producing hexoses from saccharides by enzymatic processes. The methods utilize fructose 6-phosphate and at least one enzymatic step to convert it to a hexose.

The present invention relates to a method for the production of hyaluronic acid (HA) in Bacillus subtilis and Escherichia coli through plasmid vectors wherein the gene is under the control of strong promoter Pgrac, and a system for the selection of stable bacterial strains for the production of high levels of hyaluronic acid.