摘要：Protoplast formation of lactic acid bacteria by lytic enzymes was examined. The protoplast formations of Lactobacillus jugurti OSI-1, Streptococcus lactis OSI-1, 81 and Streptococcus cremoris OSI-1, 18 were observed by treatment with lysozyme, N-acetylmuramidase SG and achromopeptidase in protoplast formation buffer (THMS buffer) containing 30mM Tris (hydroxymethyl) aminomethane-HCl buffer, 3mM MgCl2 and 0.58M sucrose. N-acetylmuramidase SG and achromopeptidase were more effective than lysozyme in the protoplast formation. On enzyme treatment, protoplast formation was better in mixed enzymes than one enzyme alone. Activity of lysozyme in protoplast formation was accelerated by the presence of α-amylase, and futhermore in the presence of N-acetylmuramidase SG and achromopeptidase. Protoplast stability was dependent on MgCl2·6H2O and sucrose in THMS buffer, because protoplast was digested according to enzyme action when MgCl2·6H2O and sucrose were not added in THMS buffer. From these results, it was possible to prepare protoplast of several strains of lactic acid bacteria for protoplast fusion by the lytic enzymes.
