Preparation and regeneration of bacteriophage PL-1 enzyme-induced Lactobacillus casei protoplasts

Lactobacillus casei ATCC 27092 protoplasts were obtained by treatment with a bacteriolytic enzyme, which was produced in the PL-1 phage lysates of this bacterium, at 37 degrees C for 1.5 h in 50 mM Tris hydrochloride buffer (pH 7.2) containing 20% sucrose and 10 mM MgSO4. The protoplasts lacked the cell wall layer but retained the ability to transport L-[3H]glutamine. The frequency of regeneration was about 1%, whereas about 99% of the cells were osmotically sensitive.