Lambda phage on mating female E. coli. Enterobacteria phage (lambda phage, coliphage) is a bacterial virus, or bacteriophage, that infects the bacterial species Escherichia coli (E. coli). The phage particle consists of a capsid, a tail, and tail fibers. The head contains the phage's double-strand linear DNA genome. During infection, the phage particle recognizes and binds to its host, E. coli, causing DNA in the head of the phage to be ejected through the tail into the cytoplasm of the bacterial cell. Magnification: 140,000x.