Streptococcus bovis (S. bovis) is one of the critical initiators of acute acidosis in ruminants. Therefore, we aimed to develop and characterize the endolysin LyJH307, which can lyse ruminal S. bovis. We tested the bactericidal activity of recombinant LyJH307 against S. bovis JB1 under a range of pH, temperature, NaCl, and metal ion concentrations. In silico analyses showed that LyJH307 has a modular design with a distinct, enzymatically active domain of the NLPC/P60 superfamily at the N-terminal and a cell wall binding domain of the Zoocin A target recognition domain (Zoocin A_TRD) superfamily at the C-terminal. The lytic activity of LyJH307 against S. bovis JB1 was the highest at pH 5.5, and relatively higher under acidic, than under alkaline conditions. LyJH307 activity was also the highest at 39 °C, but was maintained between 25°C and 55°C. LyJH307 bactericidal action was retained under 0-500 mM NaCl. While the activity of LyJH307 significantly decreased on treatment with ethylenediaminetetraacetic acid (EDTA), it was only restored with supplementation of 10 mM Ca²⁺. Analyses of antimicrobial spectra showed that LyJH307 lysed Lancefield groups D (S. bovis group and Enterococcus faecalis) and H (S. sanguinis) bacteria. Thus, LyJH307 might help to prevent acute ruminal acidosis.

中文翻译：

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内溶素LyJH307的特征是对牛链球菌具有抗菌活性。

牛链球菌（S. bovis）是反刍动物急性酸中毒的关键引发者之一。因此，我们旨在开发和表征可裂解瘤胃S的内溶素LyJH307 。牛。我们在pH，温度，NaCl和金属离子浓度范围内测试了重组LyJH307对牛链球菌JB1的杀菌活性。电脑分析显示，LyJH307具有模块化设计，在N端具有独特的酶促活性NLPC / P60超家族结构域，而在C-端则具有Zoocin A目标识别结构域（Zoocin A_TRD）超家族的细胞壁结合结构域。终奌站。LyJH307兑裂解活性S.牛 JB1在pH 5.5时最高，在酸性条件下比在碱性条件下相对更高。LyJH307活性在39°C时也最高，但保持在25°C至55°C之间。LyJH307的杀菌作用在0-500 mM NaCl下保持。用乙二胺四乙酸（EDTA）处理后LyJH307的活性显着下降，但仅通过补充10 mM Ca ²⁺才能恢复。表明LyJH307裂解兰斯菲尔德组d的抗微生物谱的分析（S. bovis型组和粪肠球菌）和H（S.血链球菌）的细菌。因此，LyJH307可能有助于预防急性瘤胃酸中毒。