Basic Guidelines for Bacteriophage Isolation and Characterization

The world is on the cusp of a post-antibiotic period. A century ago, before the advent of antibiotics, bacteriophage therapy was the treatment of choice for bacterial infections. Although bacteriophages have yet to be approved as a treatment in Western medicine, researchers and clinicians have begun to anticipate phage therapy. Bacteriophages are viruses that depend on bacterial cell metabolism to multiply. They offer a promising alternative to the use of antibiotics and an excellent antibacterial option for combating multidrug resistance in bacteria. However, not every phage is suitable for phage therapy. In particular, prophages should not be used because they can lysogenize host cells instead of lysing them. To offer adequate therapeutic options for patients suffering from various infectious diseases, a wide selection of different phages is needed. While there is no evidence of direct toxicity induced by phage particles, it is crucial to study mammalian cell-phage interactions. This requires phage preparations to be free of bacterial cells, toxins and other compounds to avoid skewing host responses. Negative staining of purified viruses and electron microscopy remain the gold standard in the identification of bacteriophages. Interestingly, genomics has greatly changed our understanding of phage biology. Bacteriophage genome sequencing is essential to obtain a complete understanding of the bacteriophages' biology and to obtain confirmation of their lifestyle. Full genetic sequencing of bacteriophage will enable a better understanding of the phage-encoded proteins and biomolecules (especially phage lytic enzymes) involved in the process of bacterial cell lysis and death. Mass spectrometry can be used for the identification of phage structural proteins. The use of lytic phages as biocontrol agents requires the most appropriate and standard methods to ensure application safety. This review pursues recent research and methods in molecular biology for the isolation and characterization of phages to facilitate follow-up and implementation of work for other researchers. Patents related to this topic have been mentioned in the text.