Brush C F, Walter M F, Anguish L J, Ghiorse W C
Department of Agricultural and Biological Engineering, Cornell University, Ithaca, New York 14853, USA.
Appl Environ Microbiol. 1998 Nov;64(11):4439-45. doi: 10.1128/AEM.64.11.4439-4445.1998.
Surface properties of Cryptosporidium parvum oocysts were investigated by using electrophoretic mobility and hydrophobicity measurements. Oocysts purified from calf feces by several sucrose flotation steps and deionized water (DI) washes (DIS method) had an electrophoretic mobility (neutral surface charge) near 0.0 m2 V-1 s-1 over a pH range of 2 to 10. The mean electrophoretic mobility of oocysts stored in DI containing a mixture of antibiotics had a lower standard deviation (sigma = 0.36) than that of oocysts stored in DI without antibiotics (sigma = 0.53); their electrophoretic mobility remained unchanged up to 121 days after collection. The electrophoretic mobility of oocysts purified on a cold Percoll-sucrose gradient after the feces was defatted with ethyl acetate (EAPS method) varied linearly with pH from 0.0 m2 V-1 s-1 at pH 2.4 to -3.2 x 10(-8) m2 V-1 s-1 at pH 10 (sigma = 0.52), thus displaying the negative surface charge at neutral pH observed by other researchers. The hydrophobicity of oocysts and two types of polystyrene beads was measured as a function of ionic strength by adhesion to polystyrene. Oocysts were purified by the DIS method. The ionic strength of the suspending solution was varied from 0 to 95 mmol liter-1. Two-week-old oocysts exhibited strong adhesion ( approximately 85%) at ionic strengths of 0 to 10 mmol liter-1 and moderate adhesion ( approximately 20%) at ionic strengths of 20 to 95 mmol liter-1. Two-month-old oocysts exhibited high adhesion ( approximately 60 to 80%) at all ionic strengths. These results show that adhesion properties governed by the electrophoretic mobility of purified C. parvum oocysts can be altered by the method of purification and that hydrophobicity can change as oocysts age.
通过电泳迁移率和疏水性测量研究了微小隐孢子虫卵囊的表面特性。经多次蔗糖浮选步骤和去离子水（DI）洗涤（DIS法）从小牛粪便中纯化得到的卵囊，在pH值为2至10的范围内，其电泳迁移率（中性表面电荷）接近0.0 m² V⁻¹ s⁻¹。储存在含有抗生素混合物的去离子水中的卵囊的平均电泳迁移率的标准偏差（σ = 0.36）低于储存在不含抗生素的去离子水中的卵囊（σ = 0.53）；采集后长达121天其电泳迁移率保持不变。用乙酸乙酯对粪便进行脱脂处理后，在冷的Percoll-蔗糖梯度上纯化的卵囊（EAPS法）的电泳迁移率随pH值呈线性变化，在pH 2.4时为0.0 m² V⁻¹ s⁻¹，在pH 10时为-3.2×10⁻⁸ m² V⁻¹ s⁻¹（σ = 0.52），因此显示出其他研究人员在中性pH下观察到的负表面电荷。通过与聚苯乙烯的粘附作用，测量了卵囊和两种类型聚苯乙烯珠的疏水性作为离子强度的函数。卵囊通过DIS法纯化。悬浮溶液的离子强度从0变化到95 mmol/L。两周龄的卵囊在离子强度为0至10 mmol/L时表现出强烈的粘附（约85%），在离子强度为20至95 mmol/L时表现出中等程度的粘附（约20%）。两个月龄的卵囊在所有离子强度下都表现出高粘附性（约60%至80%）。这些结果表明，纯化的微小隐孢子虫卵囊的电泳迁移率所决定的粘附特性可因纯化方法而改变，并且疏水性会随着卵囊老化而变化。
