Distribution of number of genes in different bacteriophages

Abstract Advent of low-cost, relatively fast DNA sequencing has opened up applications in genome sequencing. Besides benefiting sequencing of whole genomes of bacteria, archaea and fungi, it has also lend its weight to improve our understanding of bacteriophage genomes. Despite our vast amount of sequencing data, we still do not fully comprehend the generic principles that guide the evolution of genome architecture of the expansive number of bacteriophages in the microbial world. This work hopes to open a small glimpse into the mysteries surrounding the distribution of number of genes in the bacteriophage. Specifically, it attempts to construct a histogram distribution of number of genes in various bacteriophages in the hope of gleaning useful guiding principles that could help us better classify bacteriophages at the genome level. Using bacteriophage genome data obtained from GenBank, this work reveals that there is, in general, three main “size” classifications for bacteriophage genomes with genome size ranging from (43 to 143 genes), (143 to 243 genes) and (243 to 343 genes). Analysis in this study reveals that the smallest genome size is the most prevalent. Given the significant number of genes in the smallest bacteriophage genomes, there may be a need to rethink our understanding of bacteriophage, and whether they are the primitive microbial lifeforms that kickstarted the evolution of bacterial and, to a smaller extent, archaea life on Earth.