Abstract: The present disclosure provides a recombinant Bacillus subtilis for increasing the yield of menaquinone 7 (MK-7) and application thereof, and belongs to the field of genetic engineering. In the present disclosure, 14 recombinant strains BS1-BS14 are constructed through the modification of genes related to the biosynthetic pathway of MK-7 on a chromosome of Bacillus subtilis, wherein BS6-BS14 significantly increase the yield of the MK-7, reaching up to 33.5 mg/L, which is 3.53 times the yield of the original strain of wild-type Bacillus subtilis 168. The present disclosure further provides a method for modifying the MK-7 biosynthetic pathway in microorganisms to increase the yield of the MK-7, providing a theoretical basis for constructing a high-yielding strain of the MK-7.

Abstract: The present disclosure provides a recombinant Bacillus subtilis for increasing the yield of menaquinone 7 (MK-7) and application thereof, and belongs to the field of genetic engineering. In the present disclosure, 14 recombinant strains BS1-BS14 are constructed through the modification of genes related to the biosynthetic pathway of MK-7 on a chromosome of Bacillus subtilis, wherein BS6-BS14 significantly increase the yield of the MK-7, reaching up to 33.5 mg/L, which is 3.53 times the yield of the original strain of wild-type Bacillus subtilis 168. The present disclosure further provides a method for modifying the MK-7 biosynthetic pathway in microorganisms to increase the yield of the MK-7, providing a theoretical basis for constructing a high-yielding strain of the MK-7.

Abstract: A method for preparing a new crystalline form of ?-aminobutyric acid, including the steps of: S1: preparing a ?-aminobutyric acid solution at an initial concentration of 0.5-1.0 g/mL by adding crude ?-aminobutyric acid to water; adding an additive to the ?-aminobutyric acid solution, raising the temperature to 50-80° C., stirring to produce a clear solution; and S2: obtaining a suspension by evaporating water from the product of S1 under reduced pressure and at 50-80° C.; obtaining a wet product by filtering the suspension; drying the wet product to obtain the new crystalline form of ?-aminobutyric acid. The preparation method of the new crystalline form of ?-aminobutyric acid is simple, easy to operate, low in energy consumption, economical and environmentally friendly. It is suitable for large-scale industrial production.

Abstract: The present invention discloses a ?-aminobutyric acid hemihydrate crystal, its molecular formula is C4H9NO2.0.5H2O. It also discloses a method of preparing a ?-aminobutyric acid hemihydrate crystal, including first adding crude ?-aminobutyric acid to water to prepare a ?-aminobutyric acid suspension at an initial concentration of 1.2-2.0 g/mL; then stirring the suspension at a constant temperature of 5-10° C. for 6-12 hours, followed by filtering and drying to obtain the ?-aminobutyric acid hemihydrate crystal. The ?-aminobutyric acid hemihydrate crystal is stable, does not easily absorb moisture and agglomerate, and is convenient for further processing and use. The crystal has a large main particle size, uniform particle size distribution, high bulk density, good flowability, and a purity of ?99%. The preparation method of the crystal according to the present invention is simple, easy to operate, highly efficient and low in energy consumption, and is suitable for large-scale industrial production.

Abstract: A method for preparing a new crystalline form of ?-aminobutyric acid, including the steps of: S1: preparing a ?-aminobutyric acid solution at an initial concentration of 0.5-1.0 g/mL by adding crude ?-aminobutyric acid to water; adding an additive to the ?-aminobutyric acid solution, raising the temperature to 50-80° C., stirring to produce a clear solution; and S2: obtaining a suspension by evaporating water from the product of S1 under reduced pressure and at 50-80° C.; obtaining a wet product by filtering the suspension; drying the wet product to obtain the new crystalline form of ?-aminobutyric acid. The preparation method of the new crystalline form of ?-aminobutyric acid is simple, easy to operate, low in energy consumption, economical and environmentally friendly. It is suitable for large-scale industrial production.

Abstract: The present invention discloses a ?-aminobutyric acid hemihydrate crystal, its molecular formula is C4H9NO2.0.5H2O. It also discloses a method of preparing a ?-aminobutyric acid hemihydrate crystal, including first adding crude ?-aminobutyric acid to water to prepare a ?-aminobutyric acid suspension at an initial concentration of 1.2-2.0 g/mL; then stirring the suspension at a constant temperature of 5-10° C. for 6-12 hours, followed by filtering and drying to obtain the ?-aminobutyric acid hemihydrate crystal. The ?-aminobutyric acid hemihydrate crystal is stable, does not easily absorb moisture and agglomerate, and is convenient for further processing and use. The crystal has a large main particle size, uniform particle size distribution, high bulk density, good flowability, and a purity of ?99%. The preparation method of the crystal according to the present invention is simple, easy to operate, highly efficient and low in energy consumption, and is suitable for large-scale industrial production.