Cyanophages
Cyanophaga
Cyanophages are a diverse group of viruses that use cyanobacteria as hosts and are widespread in marine and limnic ecosystems. They play a crucial role in controlling cyanobacterial populations and thus significantly influence primary production in aquatic environments. By lysing their hosts, they release organic matter that is reintegrated into the microbial food web via the so-called viral shunt. Taxonomically, they are primarily assigned to the families Myoviridae, Siphoviridae, and Podoviridae within the order Caudovirales.
Details
Identification
Microscopic particles (virions) with icosahedral capsids (30–100 nm) and often a protein-based tail apparatus; detection is performed via plaque assays or metagenomics.
Social behavior
No social behavior; act as obligate intracellular parasites dependent on contact with host cells.
Diet
Cyanophages do not feed actively but parasitize cyanobacteria (e.g., Prochlorococcus, Synechococcus) by using their cellular machinery for replication.
Hunting strategy
Passive drifting in the water column and adsorption to specific surface receptors of host cells through Brownian motion.
Overwintering
Survival as free virions in the water column or sediment, often in a state of reduced infectivity at low temperatures.
Ecology
Ecological role
Regulation of algal blooms, promotion of bacterial diversity, and an essential component of the global carbon and nutrient cycle.
Natural predators
None; inactivation by UV radiation, high temperatures, and enzymatic degradation by proteases in the water.
Competitor species
Other bacteriophages or protists (grazing) that utilize the same cyanobacterial populations.
Ecosystem service
Natural control of potentially toxic blue-green algae blooms and provision of dissolved organic matter to the ecosystem.
Threats
Climate change-induced ocean warming and acidification, which can affect virion stability and host interaction.
Scientific profile
Profile
Habitat
Widespread globally in aquatic ecosystems, including marine environments (pelagic zone) and freshwater (lakes, rivers), concentrated in the euphotic zone.
Ecological role
Central role in the 'viral shunt'; they limit host populations and release organic carbon through lysis, which feeds the microbial food web.