About Bacteriophages

Bacteriophages or phages are the most abundant organisms in the biosphere and they are a ubiquitous feature of prokaryotic existence. A bacteriophage is a virus which infects a bacterium. Archaea are also infected by viruses, whether these should be referred to as ‘phages’ is debatable, but they are included as such in the scope this article. Phages have been of interest to scientists as tools to understand fundamental molecular biology, as vectors of horizontal gene transfer and drivers of bacterial evolution, as sources of diagnostic and genetic tools and as novel therapeutic agents. Unraveling the biology of phages and their relationship with their hosts is key to understanding microbial systems and their exploitation. In this article we describe the roles of phages in different host systems and show how modeling, microscopy, isolation, genomic and metagenomic based approaches have come together to provide unparalleled insights into these small but vital constituents of the microbial world. 

Phages belong to the simplest and most primitive form of life (viruses). They are extraordinarily specific for the bacterial host that they infect to propagate. They can rapidly kill this host and destroy its genetic material; as a result they produce large numbers of progeny that further decimate resident population of the bacteria causing the infection or they can make the bacteria vulnerable to classic treatment by altering its genetic material. Most importantly the killing capacity of phages are completely unaffected by classical bacterial antibiotic resistance. Phages are so small that they can penetrate and eventually disrupt bacterial biofilms. Such biofilms are a major barrier employed by bacteria against antibiotics and hence an important contributor to antibiotic resistance. Phages ability penetrate biofilms allows them to propagate to high levels in the localize centers of bacterial infection and to destroy the bacteria within them, to producing strong, but highly localized, therapeutic effect.