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.
Not all bacteria form capsules but in those that do the capsule is the interface between the bacterial cell and the external environment. As such it may serve a diversity of functions in disease including: 1. Antiphagocytosis - the smooth nature of the capsule prevents the phagocyte from adhering to and engulfing the bacterial cell. Furthermore, opsonins are prevented from binding to the cell and the process of opsonization is hindered.