Dataset of phage genes in Bacillus subtilis 168

Under unfavourable circumstances, bacteriophages that have infected a bacterial cell will undergo the lysogeny cycle. During this process, the phage genome is integrated into the host genome, with the molecular logic that the phage genome would be excised by excisionase when circumstances turn for the better as the phage enters the lytic cycle. Phage genes integrated into the host genome do not serve a useful function for the host cells, and are thus subjected to greater evolutionary pressure compared to host genes. Progressive rounds of mutations and sequence drift may thus abrogate the utility and function of the phage genes, which if repeated to many genes in the phage genome, may lead to inactivation of the prophage, with the understanding that they are no longer able to enter the lytic cycle. Besides the above, random insertion of transposon also disrupt the function of phage genes, and may even replace them with structural genes from the host genome. This work sought to profile and categorize the phage genes present in <i>Bacillus subtilis</i> 168 genome for understanding how evolutionary forces have shaped the evolution of prophages and their host. Examination of the annotated genome of <i>B. subtilis</i> 168 revealed the presence of 5 prophages. In each set of phage genes, substantial amount of evidence points to the disruption of phage genes by the action of transposons. Such effects manifest in the form of insertion of insertion element (IS) into phage genes, or the swapping of phage genes with structural genes from the host. Given the substantial number of phage genes that have been disrupted or replaced, many of the prophages in <i>B. subtilis</i> have been inactivated. But, this does not mean the evolutionary story stops here, continued presence of the phage genes in the genome of the bacterial host provides loci for the movement of host structural genes, and may represent a source of gene amplification that may have as-yet unknown effects on the host cell fitness in particular environment. <b><i></i></b>