Preparation method of mesophilic alpha-amylase

[0054] Example 1

[0055] A preparation method of medium temperature α-amylase includes the following steps:

[0056] (1) Strain activation

[0057] Inoculate the well-preserved slant strain of Bacillus subtilis 304 on the slant medium, culture at 31°C for 24 hours to activate the strain, and activate it twice;

[0058] The slant culture medium consists of 3 g beef extract, 5 g sodium chloride, 10 g peptone, 2 g glucose, 15 g agar, 1,000 mL distilled water, pH 6, and sterilization at 121°C for 20 min;

[0059] (2) Expanded cultivation of liquid seeds

[0060] ①First-level seed culture: Connect the 2 loops of slant strains after activation in step (1) into a 500ml shaker flask, with a medium volume of 100ml, a rotating shaker at 250rpm, a culture temperature of 31℃, and a culture time of 10h;

[0061] ②Secondary seed culture: Put the first-level seed into a 500ml second-level seed shaker at 10% of the inoculum, and the cultivation conditions are the same as those of the first-level seed;

[00

[0080] Example 2

[0081] A preparation method of medium temperature α-amylase includes the following steps:

[0082] (1) Strain activation

[0083] Inoculate the well-preserved slant strain of Bacillus subtilis 304 on the slant medium, culture at 35°C for 30h to activate the strain, and activate it 3 times;

[0084] The slant culture medium consists of 6 g beef extract, 8 g sodium chloride, 15 g peptone, 5 g glucose, 20 g agar, 1000 mL distilled water, pH 6.5, and sterilization at 121°C for 20 min;

[0085] (2) Expanded cultivation of liquid seeds

[0086] ①First-level seed culture: Connect the 2 loops of slant strains activated in step (1) into a 500ml shaker flask, fill the medium with 100ml, rotate the shaker at 250rpm, culture temperature 35℃, culture time 10h;

[0087] ②Secondary seed culture: Put the first-level seed into a 500ml second-level seed shaker at 10% of the inoculum, and the cultivation conditions are the same as those of the first-level seed;

[0088] ③Three-level seed cult

[0104] Example 3

[0105] A preparation method of medium temperature α-amylase includes the following steps:

[0106] (1) Strain activation

[0107] Inoculate the well-preserved slant strain of Bacillus subtilis 304 on the slant medium, culture at 37°C for 36 hours to activate the strain, and activate it 3 times;

[0108] The slant culture medium consists of 10 g beef extract, 12 g sodium chloride, 20 g peptone, 5 g glucose, 20 g agar, 1000 mL distilled water, pH 6.3, and sterilization at 121°C for 20 min;

[0109] (2) Expanded cultivation of liquid seeds

[0110] ①First-level seed culture: Connect the 2 loops of slant strains activated in step (1) into a 500ml shaker flask, with a medium volume of 100ml, a rotating shaker 250rpm, a culture temperature of 37°C, and a culture time of 15h;

[0111] ②Secondary seed culture: Put the first-level seed into a 500ml second-level seed shaker at 10% of the inoculum, and the cultivation conditions are the same as those of the first-level seed;

[0112]