A Short Introduction to Bacteriophages

First discovered in the 19th century, bacteriophages (phages) are bacterial viruses and the most widespread entities on earth. Phages have multiple important roles in maintaining the bacterial population, carbon cycling, bacterial pathogenicity, and bacterial evolution. They can be used to develop DNA and protein vaccines, novel antibiotics and antiviral drugs, and phage therapy. The International Committee on Taxonomy of Viruses categorizes phages in two major orders of Caudovirales and Ligamenvirales, including five families, nine subfamilies, 145 genera, and 684 species. The most widespread families in nature are Siphoviridae, Myoviridae, Podoviridae, and Inoviridae. Phages are morphologically categorized in two major categories of tailed and polyhedral, filamentous, or pleomorphic phages. They can have either a single- or double-strand DNA or RNA genome. Phages are important for transferring mobile genetic elements, such as virulence genes and antimicrobial resistance determinants to bacteria by transduction, and have been used to treat bacterial infections. In conclusion, phages are important entities because of their roles in bacterial metabolism and surveillance in nature. Further studies can help usobtain a better understanding of the phage mechanism in bacterial evolution.