Abstract
A method for protoplast induction with penicillin G (PCG) in Bifidobacterium bifidum Es5 was examined. Growing cells were converted into protoplasts in a nutrient broth containing PCG without addition of any osmotic stabilizers. The maximal rate of protoplast induction was approximately 50% after 6hr incubation with 1unit PCG per ml. Supplementing the PCG-treatment culture with 0.1 to 0.2M sucrose raised the induction rate to 80% or more. It is suggested that sucrose makes the bacteria more sensitive to PCG, and subsequently stabilizes the protoplasts. In addition, sucrose by itself caused a decrease in the number of viable cells but not in the turbidity of the culture without PCG.
L-colonies of strain Es5 developed from bacterial suspensions and also from protoplast suspensions inoculated on nutrient agar plates containing PCG alone or PCG and sucrose.
