EFFECTS OF CARBOHYDRATES, PROTEINS, AND BACTERIAL CELLS IN THE HEATING MEDIA ON THE HEAT RESISTANCE OF CLOSTRIDIUM SPOROGENES

Abstract

Test materials were added to (1) the heating medium and (2) the subculture medium, and the survival time in both media of 10,000 spores of C. sporogenes (ATCC 7955) were detd. at 115[degree]C. If the survival time of (1) was larger than that of (2), the effect of the added substance was considered to be a true protection. If the survival time of (1) and (2) were the same, the effect of the substance was considered to be a false protection. Glucose, sucrose, and glycerol in concn. from 10 to 50% and pectin, gum arabic, glycogen, and dextrin in concn. of 2.5% in the heating medium had no effect. Starch increased survival time slightly, but its effect was a false protection. Serum albumin, ovalbumin, peptone, and nucleic acid showed a true protective effect, but the effect decreased or disappeared as the concn. was reduced from 2.5 to 0.25%. The presence of living bacterial cells exerted a protective effect. Concn. of living cells, as large as 4 x 109 cells of Staphylococcus or 5 x 107 cells of Torula utilis per ml. was needed to increase survival time of 10,000 spores of C. sporogenes. Heat-killed cells of the same sp. did not show the protective effect. Heat-denatured albumin also exerted the protective effect, though it was not as marked as native albumin. The mechanism of the protective action is discussed.