bacterialhost

Bacterial host is a term used in microbiology to describe an organism or tissue that supports the growth, survival, or life cycle of bacteria. The concept encompasses organisms that harbor bacteria as part of their resident microbiota as well as environments in which bacteria can colonize, persist, or interact with the host. In some contexts, the phrase also refers to the cell that a bacteriophage infects to reproduce.

Bacterial hosts include humans and other animals with complex microbiomes, plants with root- or tissue-associated bacteria, and insects or other invertebrates that carry endosymbionts. Bacteria can act as commensals, mutualists, or pathogens of their hosts. In plant biology, nitrogen-fixing bacteria such as Rhizobium form nodules on legume roots and supply nitrogen, illustrating a mutualistic host–microbe interaction. In medical contexts, the human gut and other mucosal sites host diverse bacteria that influence digestion, immunity, and health.

Bacteria can also be hosts for bacteriophages, viruses that infect bacteria. The host range of a bacteriophage is determined by factors such as cell surface receptors, membrane or wall properties, and the intracellular environment. Host–pathogen dynamics are shaped by coevolution, bacterial defenses, and, in some cases, horizontal gene transfer that can alter compatibility.

Studying bacterial hosts employs culture-based assays to define host range, as well as culture-independent methods such as metagenomics and 16S rRNA sequencing. Research on bacterial hosts underpins fields from medicine and microbiome science to agriculture and biotechnology, including probiotic development and phage therapy.