摘要：The effect of Mg2+ on protoplast formation in lactic acid bacteria was examined with a mixture of both lysozyme and N-acetylmuramidase SG, as lytic enzymes. The strains used were Lactobacillus jugurti OSI-1, Lactobacillus acidophilus OSI-1, Streptococcus lactis OSI-1, 81 and Streptococcus cremoris OSI-1, 18. Protoplast stability during protoplast formation was dependent on Mg2+ and sucrose in the TH buffer (THMS buffer). 13.4-55.2% of protoplsts from all 4 strains survived in 0.58M sucrose plus TH buffer and 49.7-58.7% survived in a mixture of 3mM MgCl2 puls TH buffer. In the presence of both 0.58M sucrose and 3mM MgCl2 in the TH buffer, 72.3-90.0% of protoplasts from the 4 strains were preserved at 37°C for 90min. It bacame obvious from these results that Mg2+ has an effective role as a divalent cation in protoplast stability and fusion in lactic acid bacteria.
