Division of Electron Microscopy, ICMR-National Institute of Cholera and Enteric Diseases, Kolkata, India.
Intervirology. 2017;60(4):149-155. doi: 10.1159/000485835. Epub 2018 Jan 6.
The aim of the present study is the preliminary characterization of an El Tor vibriophage M4 (ATCC 51352-B4).
We studied the growth characteristics and sustainability of this phage under various stresses like temperature, pH, and UV. The phage morphology and phage genome were also examined using electron microscopy.
Sustainability studies showed that the phage is more stable in acidic conditions, which is very uncommon among vibriophages. Studies also showed that M4 is a thermostable phage and it is inactivated by temperatures above 60°C but, like other phages, UV has a high inactivating effect on it. Morphological and genomic studies by electron microscopy showed that this phage has a long contractile tail and a big head. The genome is linear and about 120 kb in length. The genome also has a high packaging density as the value of Vm (the volume occupied per Da of biological macromolecule) is low for this phage. The phage-bacterial interaction was studied by negative staining as well as ultrathin sectioning methods.
M4 belongs to the Myoviridae family and it is generally thermostable. It is prone to destruction by alkali and UV. It also has a large DNA which is densely packed inside of a big capsid.
本研究的目的是初步描述一株 El Tor 霍乱噬菌体 M4（ATCC 51352-B4）。
我们研究了该噬菌体在不同应激条件下（如温度、pH 值和 UV 照射）的生长特性和稳定性。还使用电子显微镜检查了噬菌体的形态和基因组。
稳定性研究表明，该噬菌体在酸性条件下更稳定，这在霍乱噬菌体中非常罕见。研究还表明，M4 是一种耐热噬菌体，在 60°C 以上的温度下会失活，但与其他噬菌体一样，UV 对其有很高的灭活作用。电子显微镜的形态学和基因组学研究表明，该噬菌体具有长的收缩尾和大头。基因组是线性的，长度约为 120kb。由于该噬菌体的 Vm 值（生物大分子每道尔顿占据的体积）较低，因此基因组具有较高的包装密度。还通过负染色和超薄切片方法研究了噬菌体-细菌的相互作用。
M4 属于肌尾噬菌体科，通常耐热。它容易被碱和 UV 破坏。它还具有较大的 DNA，这些 DNA 紧密地包装在一个大的衣壳内。
