Viruses infecting microbial hosts: Biological interactions and therapeutic, biocontrol, and environmental applications bacteriophages: Microbial parasites unleashed for pioneering applications

Food safety challenges, the rapid emergence of antimicrobial resistance (AMR), and increasing zoonotic threats have intensified the need for innovative and sustainable antimicrobial strategies. Among these, bacteriophages have re-emerged as highly specific and self-amplifying agents for controlling bacterial pathogens. However, viral parasitism in microbial systems extends beyond bacteriophages alone. In this review, we present a comprehensive perspective on viruses infecting microbial hosts, including bacteriophages, cyanophages, mycoviruses (fungi-infecting viruses), protozoan viruses, and virophages. We emphasize their classification as obligate intracellular parasites, reflecting their dependence on host cellular machinery for replication and their complex infection dynamics. Key aspects of phage biology, including host recognition, lytic activity, and microbial regulation, are discussed alongside their ecological and functional roles. Beyond therapeutic applications, microbial viruses play significant roles in food safety, agriculture, aquaculture, and environmental management. These include applications in biocontrol, bacterial typing, biofilm disruption, and the management of multidrug-resistant pathogens such as Mycobacterium and Mycoplasma. Importantly, only specific bacteriophage-based products have been granted regulatory approval, highlighting the need for careful evaluation of safety and efficacy. Furthermore, specialized viral groups such as cyanophages and virophages contribute to microbial population dynamics, influence ecosystem stability, and provide valuable model systems for studying host–virus interactions and evolutionary processes. Collectively, this review highlights viruses infecting microbial hosts as versatile biological control, therapeutic, and environmental agents, offering promising avenues for addressing global challenges in health, agriculture, and sustainability.