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.
1 Some bacteria don't have a capsule. 2  Cell wall-a thin layer (membrane) outside the plasma membrane, and within the capsule. 3  DNA (Deoxyribonucleic acid) - contains all the genetic instructions used in the development and functioning of the bacterium. 4  It is inside the cytoplasm.