中文摘要：

通过生理生化、分子生物学、单因子优化等方法研究了来自南海海域一株产中性蛋白酶菌株S-3685,并对其在250 ml摇瓶中的培养条件进行了优化。结果显示,该菌株初步确定为芽孢杆菌属（Bacillus）,发酵培养的最佳碳、氮源分别为葡萄糖10 g/L和豆面10 g/L,牛肉膏5 g/L,酵母膏5 g/L。无机盐Mg SO4·7H2O、Na2CO3、KH2PO4最佳浓度分别为0.2 g/L、2.0 g/L、1.0 g/L;菌株在培养基起始p H=7.0、4%接种量、15 ml/250 ml（v/v）装液量和30℃的条件下,发酵72 h获得较高的酶产量。在最佳培养条件下产酶量为4250 U/ml,是优化前的5倍。

英文摘要：

The S-3685 strain, a marine bacterium producing neutral protease, was screened from South China Sea. It was identified as aBacillussp. based on the morphology, the biochemical characteristics, and the 16S rDNA sequencing results. This strain was gram-positive, and the spore located in the middle had ellipse or columnar shapes. The bacterial colony was round, protuberance, and milk white on the agar culture-medium. The surface of the bacterial colony was smooth and moist （30℃, 24 h）. Over time the colony slightly shriveled bumps in the middle. The length was 2.4-3.2 microns. The strain grew under the pH 5.0-11.0, and could grow normally at the temperature 4-40℃. We then explored the fermentation conditions using a 250 ml shake flask. The optimum sources of carbon and nitrogen were glucose （10 g/L） and pulse flour （10 g/L） respectively, plus the beef extract （5 g/L） and the yeast extract （5 g/L）. The optimum concentrations of MgSO4·7H2O, Na2CO3and KH2PO4 were 0.2 g/L, 2.0 g/L and 1.0 g/L respectively. The optimum initial pH of the culture medium for the protease production was 7.0. The optimized culture conditions were： inoculums at 4%, broth content at 15 ml/250ml（v/v）, temperature at 30℃, and culture for 72 h. After the optimization, the productivity of protease was increased by 5 times （from 850 to 4250 U/ml）.