本文旨在研究枯草芽孢杆菌素Subticin 112对小鼠的急性毒性作用，并测定该细菌素单次给药的半数致死剂量（median lethal dose，LD50）或最大耐受剂量（maximum tolerated dose，MTD）。将80只体重为（20±2） g的SPF级KM小鼠随机分成4组，雌雄各占1/2，每组每只小鼠分别灌胃0.4 mL的无菌生理盐水（对照组）及相同体积、浓度分别为0.25（低浓度组）、0.50（中浓度组）和1.00 g/mL（高浓度组，且为最大给药浓度）的Subticin 112溶液。灌胃后14 d内密切观察小鼠的反应。试验结束后记录小鼠的体重变化，眼球采血法收集小鼠血液，进行血清生化指标的测定，解剖后分别取心脏、肝脏、脾脏和肾脏等器官称重以测定其脏器系数，每组随机取2只小鼠（雌雄各1只）的心脏、肝脏、脾脏和肾脏等器官用于制作病理组织切片。给药14 d后，各组小鼠均正常生长且未表现出任何中毒症状。试验组小鼠增重与对照组相比，虽然有下降的趋势，但差异不显著（P>0.05）；试验组小鼠的脏器系数、血清生化指标等与对照组相比差异均不显著（P>0.05）；观察试验组小鼠的心脏、肝脏、脾脏和肾脏等器官的病理组织切片也均未出现任何病变或坏死细胞。由此可见，Subticin 112对小鼠的MTD大于20 g/kg BW，根据急性毒性试验国家标准（GB 15193.3—2003）中的急性毒性剂量分级表，Subticin 112属于无毒药物。
This experiment was conducted to evaluate the acute toxicity of the bacteriocin Subticin 112 secreted by Bacillus subtilis, and to determine the medium lethal dose (LD50) or maximum tolerated dose (MTD) in mice after oral administration. Eighty SPF KM mice with body weight of (20±2) g were randomly divided into four groups with the ratio of male∶female as 1∶1 for each group. Mice in the control group were given 0.4 mL of sterile saline, and mice in the other three experimental groups were given 0.4 mL 0.25, 0.50 and 1.00 g/mL subticin 112 solution, respectively. After oral administration, the symptoms and mortality were observed and recorded carefully for 14 days. After the experiment, we recorded the weight gain, and then blood samples were collected from the eye vein by quickly removing the eyeball to determine the biochemical indices in serum. After dissecting all the mice, the heart, liver, spleen and kidney were weighed accurately to determine the organ coefficient, and 2 organ samples of each group were picked for histopathology examination. After oral administration for 14 days, the mice in each group were alive and did not show any abnormal symptoms. The weight gain of mice in experimental groups had a decreasing trend (P>0.05). Organ coefficients and biochemical indices in serum of mice in each group were not significantly different (P>0.05). And according to the results of histopathology examination, no pathological changes were observed. Through the experiment, we conclude that the maximum tolerated dose (MTD) of the bacteriocin Subticin 112 is higher than 20 g/kg BW. According to the national standard of acute toxicity test (GB 15193.3—2003), Subticin 112 belongs to a non-toxic medicine. ［Chinese Journal of Animal Nutrition, 2011, 23（8）：1446 -1452］
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