Propagate the culture in Brain Heart Infusion broth and when you find moderate turbidity,add 15% sterile glycerol at completely asceptic conditions and keep culture in deep freez. Also another way , add few cell suspension to sterile glass beads and keep in deep freez at -20 degree
Thank you very much Dr. Gamal Enan for your answer, but how can I deal with these strains when I want to prepare for the tests or extra studies, for ex. biochemical tests or some virulence studies.
Take by steril forceps two glass beads and put asceptically in sterile BHI broth or pipette i ml from cell suspension stored in glycerol after its propagation in incubator for 6 hours and incubate overnight and subculture another time to get young viable cells to work for any test