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.
Encapsulated bacteria have capsules which serve as an antiphagocytic virulence factor. These bacteria include S. pneumoniae, H. influenzae type B, N. meningitidis, E. coli, Salmonella, K. pneumoniae, group B Strep, B. fragilis, and C. Neoformans.