<p><font color="#000000">The <strong>phi X 174</strong> (or <strong>phi X</strong>) bacteriophage was the first organism to have its DNA-based <font color="#810081">genome</font> sequenced, by Fred Sanger and his team in 1977.<sup class="reference" id="cite_ref-0">[1]</sup> In 1962, Walter Fiers had already demonstrated the physical, covalently closed circularity of phi X 174 DNA.<sup class="reference" id="cite_ref-1">[2]</sup></font></p><p><font color="#000000">This phage has a very small amount of DNA. It has 11 genes in 5386 bases (it is single stranded) in a circular topology. Several of them expressing similar function in two groups. The GC-content is 44% and 95% of nucleotides are coding genes.</font></p>