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.
Mycobacterium: A large family of bacteria that have unusually waxy cell walls that are resistant to digestion. The mycobacteria includes: 1  Mycobacterium avium -- which causes tuberculosis-like illness in birds and immunodeficient people;2  Mycobacterium leprae -- which causes leprosy;ycobacterium: A large family of bacteria that have unusually waxy cell walls that are resistant to digestion. The mycobacteria includes: 1  Mycobacterium avium -- which causes tuberculosis-like illness in birds and immunodeficient people;