家蚕肠道枯草杆菌产蛋白酶的发酵条件与酶学性质

肠道微生物分泌的蛋白酶可促进家蚕对桑叶养分的消化吸收，枯草芽孢杆菌是家蚕肠道内一种重要的产蛋白酶菌株。为提高枯草芽孢杆菌蛋白酶的高效利用，对该菌株适宜发酵条件及酶学性质进行了研究。结果表明：各因素对枯草芽孢杆菌产酶活性影响的大小顺序依次为：pH值〉培养温度〉培养时间〉装液量；最适的产酶条件为：pH=7，培养温度：30 ℃，培养时间：36 h；对枯草芽孢杆菌产蛋白酶进行初步提纯后并研究得出该酶反应的最适pH 10.0，最适反应温度为：60 ℃；该酶为碱性蛋白酶、不耐高温、不耐酸，但在35 ℃条件下热稳定性较好。

Appropriate Culture Conditions of Bacillus subtilis Secreting Protease from Silkworm Intestine and Some Properties of the Protease

Protease secreted by intestinal microbes can promote the silkworm nutrient digestion and absorption on mulberry. Bacillus subtilis is an important silkworm gut protease producing strain. In order to improve the development and utilization of silkworm gut microbes, conditions suitable for protease strain and enzyme properties were studied. The results showed that the order of the degree of the effection of various factors on the activity of protease secreting from Bacillus subtilis was pH 〉 culture temperature〉 incubation time 〉 loaded liquid volume. The optimal conditions for enzyme production were pH： 7.0, culture temperature ：30 ℃, incubation time ：36 h. After the preliminary purification of the protease, the enzyme properties were studied . It indicated that the best pH for this enzyme was 10 and the optimum reaction temperature was 60 ℃. The enzyme was alkaline protease , not heat-resistant and not acid –resistant, but well stable at 35 ℃.