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.
The chemical nature of the capsule is important in the functions the capsule plays in the infection process. The capsules of bacteria are chemically diverse but the majority of them are polysaccharide in nature. These polymers are composed of repeating oligosaccharide units of two to four monosaccharides.