[Protoplast isolation from a nisin-forming culture of Streptococcus lactis strain MGU]

A procedure for protoplasts of Str. lactis producing nisin was developed. The following lysing factors were used for obtaining the protoplasts: lycozyme, LE enzyme, lysosubtilin and an enzyme isolated from the culture fluid A. levoris. The use of the above factors in different combinations provided an increase in the number of the formed protoplasts from 1-2 in the field of the microscope vision to 15-20, which amounted to 25 per cent of the total number of the cells visible under microscope.