Using different Sinorhizobium meliloti strains as hosts, we isolated eight new virulent phages from the rhizosphere of the coastal legume Medicago marina. Half of the isolated phages showed a very narrow host range while the other half exhibited a wider host range within the strains tested. Electron microscopy studies showed that phages M_ort18, M_sf1.2, and M_sf3.33 belonged to the Myoviridae family with feature long, contractile tails and icosaedral head. Phages I_sf3.21 and I_sf3.10T appeared to have filamentous shape and produced turbid plaques, which is a characteristic of phages from the Inoviridae family. Phage P_ort11 is a member of the Podoviridae, with an icosahedral head and a short tail and was selected for further characterization and genome sequencing. P_ort11 contained linear, double-stranded DNA with a length of 75239 bp and 103 putative open reading frames. BLASTP analysis revealed strong similarities to Escherichia phage N4 and other N4-like phages. This is the first report of filamentous and N4-like phages that infect S. meliloti.

中文翻译：

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紫花苜蓿根际中华根瘤菌 (Ensifer) 苜蓿噬菌体的多样性：肌病毒、丝状病毒和 N4 样足病毒。

使用不同的苜蓿中华根瘤菌菌株作为宿主，我们从沿海豆科植物紫花苜蓿码头的根际分离出八种新的强毒噬菌体。一半分离的噬菌体显示出非常窄的宿主范围，而另一半在测试的菌株中显示出更广泛的宿主范围。电子显微镜研究表明，噬菌体 M_ort18、M_sf1.2 和 M_sf3.33 属于肌病毒科，具有长而可收缩的尾部和二十面体头部。噬菌体I_sf3.21和I_sf3.10T似乎具有丝状形状并产生浑浊斑块，这是来自Inoviridae家族的噬菌体的特征。噬菌体 P_ort11 是足病毒科的成员，具有二十面体头部和短尾，被选择用于进一步表征和基因组测序。P_ort11包含线性双链DNA，长度为75239 bp和103个假定的开放阅读框。BLASTP 分析显示与埃希氏菌噬菌体 N4 和其他 N4 样噬菌体有很强的相似性。这是首次报道丝状噬菌体和 N4 样噬菌体感染苜蓿中华根瘤菌。