Recovery of heat-injured spores of Clostridium perfringens types B, C and D by lysozyme and an initiation protein

Heat-injured spores of several strains of Clostridium perfringens types B, C and D could be partially recovered if lysozyme was included in the recovery medium. As little as 25 ng ml-1 was effective. D90 degrees C values of 1.3-2.6 were obtained with an approximate 2-3-fold increase in the presence of 1 /microgram ml-1 of lysozyme. In the absence of lysozyme, prolonged heating of spores resulted in the appearance of satellite colonies surrounding colonies of surviving spores. An initiation protein, previously reported in the case of type A strains, was also produced by type B, C and D strains. When added to the recovery medium it too promoted the recovery of spores from thermal injury though not as effectively as lysozyme.