鱼源副乳房链球菌前噬菌体裂解酶Sply828的抗菌活性

Antibacterial activity of a prophage lysin Sply828 from fish-derived Streptococcus parauberis

摘要:

【背景】副乳房链球菌(Streptococcus parauberis)是重要的水产病原菌，该病原菌已逐渐出现新的血清型及多重耐药性状，因此亟须开发出一种新的抗菌药物用于该病害的防治。研究发现，前噬菌体编码的裂解酶能够有效地杀死其宿主，具有良好的抗菌应用前景。【目的】以副乳房链球菌前噬菌体裂解酶为对象，研究其杀菌宿主谱并优化其裂解活性的条件。【方法】利用PHASTER工具对副乳房链球菌菌株KRS02083全基因组序列分析发现，其前噬菌体包含一种裂解酶的基因Sply828；通过基因克隆、表达和纯化等技术得到裂解酶Sply828蛋白；通过浊度递减实验探究裂解酶Sply828对不同细菌的杀菌活性及其最适的裂解条件。【结果】裂解酶Sply828对鱼源副乳房链球菌具有最佳的杀菌活性，并发现该酶对处于指数生长期的细菌杀菌效果最好；其最适裂解温度为28℃，最适pH为6.2；Ca²⁺和Mg²⁺对该酶的杀菌活性有促进作用，但是Zn²⁺、Cu²⁺、Fe²⁺、Ni²⁺明显抑制该酶的杀菌活性。【结论】基于全基因组数据分析发现，前噬菌体裂解酶Sply828具有高效、特异杀菌活性，为防控水产副乳房链球菌病害提供了基础。

Abstract:

[Background] Streptococcus parauberis is a major aquatic pathogen which has gradually evolved new serotypes and multi-drug resistance. Therefore, it is urgent to develop a new antibacterial drug for the prevention and treatment of the disease caused by this pathogen. Studies have demonstrated that a lysin encoded by a prophage can effectively kill the host and has a good prospect of antibacterial application. [Objective] In this paper, we investigated the host spectrum of the prophage lysin from S. parauberis and optimized the conditions for the lytic activity. [Methods] We used bioinformatics tools to analyze the whole genomic sequence of the S. parauberis strain KRS02083 and discovered a lysin gene Sply828. By gene cloning, protein expression and purification, we obtained the lysin Sply828. We then evaluated the activities against different bacteria and the optimal lysis conditions of Sply828 by performing the turbidity decrease assay. [Results] Sply828 displayed the best activity against fish-derived S. parauberis and exhibited the highest activity against the bacteria in the exponential growth phase. This enzyme had the highest activity at 28 °C and pH 6.2, and its activity can be improved by Ca²⁺ and Mg²⁺ while inhibited by Zn²⁺, Cu²⁺, Fe²⁺, and Ni²⁺. [Conclusion] The prophage lysin Sply828 existing in the genomic sequence of S. parauberis possesses efficient and specific bactericidal activity, providing a preliminary basis for the prevention and control of the disease caused by S. parauberis.