一株奶牛乳房炎源链球菌噬菌体P27的分离及生物学特性分析

Isolation and Characterization of a Streptococcus Bacteriophage p27 from Cow Mastitis Cases

本试验旨在分离奶牛乳房炎源链球菌裂解性噬菌体,并对其进行生物学特性测定及比对分析。以实验室保存的奶牛乳房炎源链球菌为宿主菌,从新疆石河子地区奶牛场粪便、污水及奶牛饮用水中分离纯化裂解性噬菌体。利用双层琼脂平板法测定其裂解能力、最佳MOI、一步生长曲线的变化、热稳定性、酸碱耐受性等,并对结果进行比对分析。本试验中分离纯化出了1株裂解性噬菌体。使用透射电子显微镜观察P27其头部长约76.2 nm,尾长约153.1 nm,为常见的肌尾噬菌体,将其命名为vB_SMC_P27(简称P27)。P27最佳MOI为10℃、60℃下50 min活性丧失;在pH4.0~12.0时,噬菌体P27活性未有明显下降;裂解量约为156 PFU/cell,潜伏期约为15 min,爆发期约为140 min。其对奶牛乳房炎源链球菌的裂解率为33.33%(6/18)。P27裂解效果较好,增殖迅速,在生产中具有防治奶牛乳房炎源耐药链球菌的潜力。

The purposes of this study were to isolate the lytic phages from dairy cows of Streptococcusmastitis,and to conduct biological characterization.Using laboratory-preserved bacteria from Streptococcus mastitis cases,the lytic phages were isolated and purified from feces,sewage and drinking water of dairy cows in Shihezi,Xinjiang.The double-layer agar plate method was used to determine the lysis capacity,MOI,change of one-step growth curve,thermal stability,acid-base tolerance,etc.In this experiment,a lytic phage P27 was isolated and purified.The transmission electron microscopy found that P27 had a head of about 76.2 nm and a tail of about 153.1 nm.It was a common myophage and named as vB_SMC_P27(referred to as P27).The best MOI of P27 was 10℃,and its activity lost at 60℃ for 50 min.However,the phage P27 did not decrease its activity significantly at pH4.0~12.0.Other features of the phage P27 included the cracking amount of about 156 PFU/cell,the incubation period for about 15 min and the burst period for about 140 min.In addition,P27 had a lysis rate of 33.33%(6/18)for Streptococcus from cow mastitis.These results showed that P27 had a good cracking effect and rapid proliferation.The discovery of the phage P27 provided the potential to prevent and treat cow mastitis caused by drug resistant Streptococcus.