PROTOPLAST FORMATION AND REGENERATION IN LACTOBACILLUS CASEI.

The conditions for the protoplast formation and the cell wall regeneration of Lactobacillus casei IFO-3831 are described. Since L. casei was resistant to the action of lysozyme, the cell wall digestion was insufficient when the cells were treated with lysozyme at various concentrations. The protoplasts were successfully produced by the treatment with mutanolysin. Approximately 100% of protoplast forming ratio was achieved when the cell suspension was incubated in the presence of 50 unit/ml of the enzyme in 5 mM Tris-maleate-0. 09 M sucrose solution (pH 6. 2) at 37 degree C for 60 min. The burst of protoplasts and the autolysis of cells happened in the buffer solution containing mutanolysin without magnesium ion, but they were restrained by addition of 10 mM magnesium ion as a final concentration to the buffer solution. The protoplast regeneration was achieved when the samples were diluted and spread over the surface of a regeneration medium. 1. 41% of the cells retained osmotic stability. The regeneration ratio of protoplasts was 1. 8%.