牛乳铁蛋白抗菌活性及其影响因素的研究

乳铁蛋白具有广谱的抗菌性 ,它通过直接性的“铁剥夺”和间接性的“膜渗透”2种机制发挥抗菌作用。文中开展了牛乳铁蛋白抗菌活性的研究 ,研究表明 ,牛乳铁蛋白对大肠杆菌的最小抑菌浓度为 2mg/mL ,对金黄色葡萄球菌的最小抑菌浓度为 1 6mg/mL。葡萄糖、蔗糖、麦芽糖、牛血清白蛋白 (BSA)、尿素、硫酸铵在 0～ 1 0mg/mL ,乳糖、可溶性淀粉在 0～ 4mg/mL ,酪蛋白在 0～ 1 2mg/mL的质量浓度范围内 ,对牛乳铁蛋白的抗菌活性影响不大。当NaCl或KCl的浓度为2 5～ 1 0 0mmol/L ,MgCl2 或CaCl2 的浓度为 1 0～ 5 0mmol/L时 ,牛乳铁蛋白的抗菌活性就会大大降低。随着缓冲盐浓度和有机酸浓度 (2 5～ 1 0 0mmol/L)的增大 ,牛乳铁蛋白的抗菌活性呈下降趋势 ,且在微碱性pH环境下牛乳铁蛋白表现出较强的抗菌活力。

Study on the Antibacterial Activity and Its Influential Factors of Bovine Lactoferrin

It has been shown that lactoferrin is bacteriostatic against a wide range of microorganisms. Lactoferrin exerts its antibacterial activity in two ways. The first mechanism is by depriving the microorganisms from iron needed for growth; the second mechanism is by direct binding to the microbial membrane. In this paper, the antibacterial activity of lactoferrin was studied. It was found that the MIC of bovine lactoferrin against E.coli and S. aureus is 2?mg/mL and 1.6?mg/mL, respectively. Glucose, sucrose, maltose, BSA, urea, ammonium sulphate at concentration 0～10?mg/mL, lactose, starch at concentration 0～4?mg/mL and casein at concentration 0～1.2?mg/mL have no effect on the antibacterial activity of lactoferrin. Its antibacterial effectiveness was reduced in the presence of NaCl or KCl at concentration 25～100?mmol/L, MgCl 2 or CaCl 2 at concentration 1.0～5.0 mmol/L in the buffer. Its effectiveness declined with the increasing of buffer concentrations or carboxylic acids within the range of 25 to 100?mmol/L. The protein was most active under slightly alkaline conditions.