T4 phage
Escherichia virus T4
T4 phage is a virus that specifically infects and destroys bacteria of the species Escherichia coli. It belongs to the Myoviridae family and is characterized by a highly complex structure consisting of an icosahedral head and a contractile tail assembly. As an obligately lytic phage, its replication within the host cell inevitably leads to lysis and the release of new virions. For decades, it has served as one of the most important model systems in molecular biology, genetics, and virology.
Details
Identification
Icosahedral head (approx. 120 nm long), long contractile tail (approx. 100 nm) with a baseplate and six long tail fibers for adsorption.
Social behavior
Solitary particles; interaction occurs exclusively with the host cell during the infection cycle.
Diet
Obligate parasite; utilizes the cellular machinery of Escherichia coli for the replication of its genome and the synthesis of capsid proteins.
Hunting strategy
Adsorption to lipopolysaccharides and OmpC proteins on the host surface via tail fibers, followed by DNA injection through the tail tube.
Spawning substrate
Cytoplasm of living Escherichia coli bacteria.
Overwintering
Persistence as an inactive virion in the environment or through continuous infection cycles in host populations.
Ecology
Ecological role
Regulation of bacterial populations in aquatic systems and the intestinal tract of animals; contribution to the microbial loop and nutrient cycling.
Natural predators
No predators; inactivation by UV radiation, heat, or bacterial defense mechanisms such as restriction enzymes and CRISPR.
Competitor species
Other coliphages (e.g., T7, Lambda phage) competing for the same host resources.
Ecosystem service
Control of potentially pathogenic bacteria and release of organic matter through bacterial lysis.
Threats
Environmental factors such as extreme pH values, high temperatures, and UV light, as well as the development of bacterial resistance.
Scientific profile
Profile
Habitat
Ubiquitous in habitats with high E. coli density, particularly in municipal sewage, liquid manure, the intestinal tract of mammals, and fecally contaminated soils and waters.
Ecological role
Regulation of bacterial populations; part of the 'viral shunt' in the microbial food web, recycling organic carbon from bacteria back into dissolved nutrients.