摘要
目的:耐甲氧西林金黄色葡萄球菌(methicillin-resistant Staphylococcus aureus,MRSA)是临床最常见的耐药病原体之一,研究其噬菌体对治疗由多重耐药菌MRSA引起的细菌感染具有重要应用价值.方法:以一株多重耐药菌MRSA38为宿主菌分离新型噬菌体,分析该噬菌体的生物学特性和全基因组序列,并通过体外试验评价该噬菌体的抑菌效果.结果:从医院污水中分离获取一株能高效裂解MRSA的新型噬菌体,命名为BUCT_X001.透射电子显微镜结果显示BUCT_X001具有正二十面体头部(50 nm)和不可收缩尾部(250 nm).该噬菌体的生理特性测定结果表明,其最佳感染复数为0.01,潜伏期为15 min,对数生长期为150 min,平均裂解量为54.7 PFU/cell.BUCT_X001具有较强pH稳定性与温度耐受性,在pH 5.0～9.0和温度4～45℃范围内处理后能保持稳定活性.该噬菌体的宿主范围较广,能裂解17株MRSA菌.此外,BUCT_X001的抑菌效果与MOI呈依赖性,即使当MOI仅为0.01时,BUCT_X001仍能在4 h内使培养液OD00值下降到0点附近,并维持效果直到8 h.BUCT_X001的全基因组结果显示,其总长度为42 649 bp,G+C含量为34％,该基因组编码68个开放阅读框.系统发育树结果表明BUCT_X001与Caudoviricetes科Bronfenbrennervirinae亚科噬菌体SAP_1432序列相似度最高,全基因组覆盖率为61％,序列一致性为97.38％.结论:分离出一株可高效裂解MRSA的噬菌体BUCT_X001,该噬菌体对宿主菌具有较强杀伤效果,有望用于预防与治疗由MRSA引起的细菌感染.
Abstract
Objective:Methicillin-resistant Staphylococcus aureus is one of the most important foodborne pathogens.The in-depth study of phage is of great value in the treatment of MRSA infection.Methods:MRSA38 was used as the host and a new phage was isolated from hospital sewage.The biological characteristics of the newly isolated phage were determined and its whole genome sequence was analyzed.The antibacterial effect of this phage on MRSA38 was assessed in vitro.Results:A new phage infecting MRSA38 was successfully isolated and named BUCT_X001.It has a 50 nm head and a 250 nm tail.It has an optimal multiplicity of infection of 0.01.The one-step growth curve shows that BUCT_X001 had a latency of 15 min,a rise phase of 150 min,and a burst size of 54.7 PFU/cell.BUCT_X001 can maintain more than 90％activity over a wide pH(5.0 to 9.0)and temperature(4℃ to 45℃)range.Whole genome analysis of BUCT_X001 reveals that it has a total length of 42 649 bp,with a(G+C)％content of 34％and it is predicted to encode 68 open reading frames.Phylogenetic tree results show that BUCT_X001 is a novel bacteriophage of the subfamily Bronfenbrennervirinae in the family Caudoviricetes.Conclusions:A new phage targeting MRSA was isolated and showed strong antibacterial effects on the growth of host bacteria.It has great potential for use in the prevention and treatment of infections caused by MRSA in clinical settings.
NETL
NSTL
万方数据