Abstract

Bacteriophages are the most abundant entity on the planet and play very relevant roles in the diversity and abundance of their bacterial hosts. These interactions are subject to several factors, such as the first encounter of the phage with its host bacterium, in which molecular interactions are fundamental. Along with this, these interactions depend on the environment and other communities present. This chapter focuses on these phage–bacteria interactions, reviewing the knowledge of the early stage (receptor-binding proteins), host responses (resistance and counter-resistance), and ecological and evolutionary models described to date. In general, knowledge has focused on a few phage–bacteria models and has been deepened by sequencing and metagenomics. The study of phage–bacteria interactions is an essential step for the development of therapies and other applications of phages in the clinical and productive environment.