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.
Listeria monocytogenes: It is a small Gram positive rods arranged in V or L shaped formations similar to corynebacteria Spirochetes (Treponema, Leptospira, and Borrelia): Thin walled, flexible, spiral rods (Corkscrew shaped) seen only by darkfield microscope and generally not seen in standard light microscope.