Definition of retain. transitive verb. 1a : to keep in possession or useb : to keep in one's pay or service; specifically : to employ by paying a retainerc : to keep in mind or memory : remember.
However, some gram- positive bacteria may also have capsules. Examples for gram-negative bacteria with capsules: Escherichia â¦coli, Klebsiella pneumoniae, Salmonella. Examples for gram-positive bacteria with capsules : Bacillus megaterium, Streptococcus pyogenes, Sterptococcus pneumoniae.
Bacteriophages occur abundantly in the biosphere, with different virions, genomes and lifestyles. Phages are classified by the International Committee on Taxonomy of Viruses (ICTV) according to morphology and nucleic acid.Nineteen families are currently recognized by the ICTV that infect bacteria and archaea. Of these, only two families have RNA genomes and only five families are enveloped.n this electron micrograph of bacteriophages attached to a bacterial cell, the viruses are the size and shape of coliphage T1. To enter a host cell, bacteriophages attach to specific receptors on the surface of bacteria, including lipopolysaccharides, teichoic acids, proteins, or even flagella.