A study to investigate the correlation of abundance between the spacers and the prophages in bacterial genome

Abstract

Bacteriophages, the most abundant and diverse entities in the biosphere which are composed of a nucleic acid molecule that is surrounded by a protein structure. These viruses can infect or kill bacteria through lytic and lysogenic cycle, however, the bacteria have evolved their own defense system to protect themselves from the integration of foreign mobile genetic elements through CRISPR-Cas that utilizes short foreign DNA sequences, known as spacers. Since it is their defense mechanism, therefore the correlation of abundance between the spacers and the prophages are expected to be inversely proportional. The project was designed to find the relationship between the total number of spacers and the prophages through computational approach. The finding of this thesis conflict with expected outcome since regression line do not demonstrate significant changes when analyzed. Moreover, almost 33% bacterial genomes were found to carry prophages even in the presence of spacers those align with them and the number of spacers increases with the increase of prophage length. In spite of being present in bacterial genome along with spacers, they do not share any core genes indicate that not any specific types of prophages have these special capacity to infect bacteria in presence of spacer rather they are of different species.