家蚕肠球菌体外抑制微孢子发芽的动力学研究

Kinetic Studies of Enterococci Inhibition on the Germination of Nosema bombycis Spores

研究表明,家蚕微孢子的浓度(y)与孢子悬浮液的吸光值(OD_(625))(x)之间的函数关系可用y=2.712×1O^6x来表示,即可用分光光度计法快速准确地测定孢子的发芽率。微孢子在不同处理液中发芽的动力学曲线显示:经磷酸缓冲液、培养基的透析液或培养基的20％～80％饱和废硫酸铵盐析蛋白质处理微孢子在8min之内快速发芽;而经肠球菌培养上清液的透析液或培养上清液的20％～80％饱和度硫酸铵盐析蛋白质处理的微孢子在30min内发芽十分缓慢,两者对孢子发芽的最终相对抑制率分别达到65.95％和70.08％;抑制微孢子发芽的活性物为肠球菌的外分泌物,其分子量在3.5kD以上,具有良好的热稳定性。研究结果初步揭示了肠球菌外分泌物质抑制家蚕微孢子发芽的动力学机制。

Based on the linearity relationship ( y - 2. 712 x 106x) between the concentration(spores/mL) and OD625 of Nosema bombycis spores suspension, the inhibiting activity of enterococci against the germination of Nosema bombycis spores was monitored by continuous spectrophotometric recording of germinating spores suspensions. Both the cultured supernatant of enterococci and the proteins precipitated by (NH4)2SO4 from the supernatant showed strong inhibiting activity. The spores treated with the supernatant or the precipitated proteins germinated slowly during the initial 30 min,and the ultimate germination percentage decreased about 65.95% and 70.08%.It revealed that the enterococci isolated from intestine of silkworm larvae could secret active substance during its growth. The molecular weight of such substance was estimated to be above 3.5 kD and was found to be thermostable. The results of this research revealed initially kinetic mechnism of the substance secreted by enterococci of inhibition aganist germination of Nosema bombycis spores.