芽孢杆菌的产酶特性及其对抗生素的耐受性

以4株枯草芽孢杆菌（Bacillus subtilis）和2株地衣芽孢杆菌（Bacillus licheniformis）为研究对象，通过测定其成胞率、中性蛋白酶活性及对24种抗生素的耐受性，从中筛选优良芽孢杆菌。结果表明，从6株芽孢杆菌中筛选得到3株成胞率和产中性蛋白酶均较好的芽孢杆菌，分别为枯草芽孢杆菌BLCC1-0552、BLCC1-0615和地衣芽孢杆菌BLCC1-0441，液体发酵24 h后，成胞率较高，均达到98%；中性蛋白酶活性分别为90.58 U/mL、100.32 U/mL和24.72 U/mL。其中，枯草芽孢杆菌BLCC1-0615固体发酵玉米-豆粕型常规饲料产中性蛋白酶活力最高，发酵48 h时达到2 154.49 U/g。3株芽孢杆菌对抗生素的耐受性不一致，其中枯草芽孢杆菌BLCC1-0615对24种抗生素中的17种表现敏感，敏感率最高为70.83%。因此，确定优良菌株为枯草芽孢杆菌BLCC1-0615，其成胞率、产中性蛋白酶能力好及对抗生素耐受性较低，具有作为饲料添加剂应用于畜禽饲料中的潜力。

Enzyme-producing characteristic and antibiotic tolerance of Bacillus

Using 4 strains of Bacillus subtilis and 2 strains of Bacillus licheniformis as research objects, the cell formation rate, neutral protease activity and resistance to 24 antibiotics were determined to screen the excellent Bacillus strain. The results showed that 3 strains of Bacillus with higher cell formation rate and neutral proteinase activity were selected from 6 strains of Bacillus, which were B. subtitles BLCC1-0552, B. subtitles BLCC1-0615 and B. licheniformis BLCC1-0441. After fermentation for 24 h, the cell formation rate was high and reached 98%, and the neutral proteinase activity was 90.58 U/ml, 100.32 U/ml and 24.72 U/ml, respectively. Among them, the neutral protease activity of the corn-soybean meal type conventional feed solid-fermented by B. subtilis BLCC1-0615 was the highest, reaching 2 154.49 U/g at 48 h of fermentation. The 3 strains of Bacillus had different tolerance to antibiotics, particularly B. subtilis BLCC1-0615, which was sensitive to 17 kinds of 24 detected antibiotics, and the highest susceptibility rate was 70.83%. Therefore, the B. subtilis BLCC1-0615 was determined as the excellent strain, which had good cell formation rate, neutral protease ability and low tolerance to antibiotics, indicating this strain had the potential to be used as a feed additive in livestock and poultry feed.