bakteriiyofajlar

Bakteriiyofajlar, also known as bacteriophages, are viruses that specifically infect and replicate within bacterial cells. The term derives from the Greek words for “bacteria” and “phage,” meaning “eater.” They are among the most abundant biological entities on Earth, with estimates of several trillion phages per milliliter of seawater. The vast majority of bacteriophages are lytic, meaning that after hijacking a host’s replication machinery they produce new phage particles and ultimately lyse the bacterial cell. A minority are lysogenic, integrating their genome into the host chromosome and replicating along with the host until triggered to enter the lytic cycle.

Typical phage morphology consists of a nucleic acid core protected by a protein capsid, sometimes with a tail structure that aids attachment and penetration of the bacterial cell envelope. The genome is often a double‑stranded DNA in the majority of tailed phages, but single‑stranded RNA and DNA phages also exist. Phages are highly specific to bacterial species or strains, determined largely by host receptor recognition on the phage tail proteins. This specificity has made phages useful tools for bacterial identification and typing in clinical microbiology.

In biotechnology, phages serve as vectors for gene delivery, as catalysts for site‑specific recombination, and as antibacterial agents in phage therapy, an area regaining interest due to rising antibiotic resistance. Phage-display technology has enabled the discovery of peptides and antibodies with high affinity for target molecules. Environmental and ecological studies use phages as indicators of microbial diversity and as natural regulators of bacterial populations in ecosystems ranging from oceans to soil and the human gut.

The discovery of bacteriophages in the early 20th century by Frederick Twort and later by Felix d’Herelle opened virology to a new class of viruses. Since then, advances in genomics and nanotechnology continue to uncover novel phage types and broaden their applications in medicine, industry, and fundamental science.