Microviruses
Microviridae
Microviridae is a family of viruses that infect bacteria and possess a circular, single-stranded DNA genome. They are characterized by a small, non-enveloped icosahedral capsid with a diameter of approximately 25 to 30 nanometers. A well-known member of this family is the bacteriophage phiX174, which was the first organism to have its genome fully sequenced. These viruses play a significant role in microbial ecology by regulating bacterial populations in diverse environments.
Details
Identification
Icosahedral capsid with T=1 symmetry; often featuring prominent protein spikes at the 12 vertices of the icosahedron; genome consists of circular ssDNA.
Diet
Obligate parasites of bacteria (e.g., Enterobacteria, Chlamydia, Spiroplasma); they utilize the host cell's replication machinery.
Hunting strategy
Adsorption to specific receptors on the bacterial cell wall and injection of the viral genome.
Ecology
Ecological role
Regulation of bacterial density in aquatic and terrestrial ecosystems as well as in the human microbiome; contribution to horizontal gene transfer.
Natural predators
Degradation by enzymes (proteases/nucleases) in the environment or inactivation by UV radiation.
Competitor species
Other bacteriophage families that infect the same host bacteria.
Ecosystem service
Control of pathogenic bacteria and maintenance of microbial balance.
Threats
Environmental factors such as extreme heat or pH levels that denature the capsid.
Scientific profile
Profile
Habitat
Microviridae are ubiquitously distributed. They are found in marine and freshwater environments, in soil, and in significant quantities within the gut microbiome of humans and animals (virome).
Ecological role
Microviridae play an important role in controlling bacterial populations and influencing microbial community structure. They contribute to horizontal gene transfer and are part of the 'viral shunt,' which makes organic matter available to other microorganisms.