EFFECTS OF CARBOHYDRATES, PROTEINS, AND BACTERIAL CELLS IN THE HEATING MEDIA ON THE HEAT RESISTANCE OF CLOSTRIDIUM SPOROGENES
It is well known that the heat resistance of bacterial spores is influenced markedly by the nature of the medium in which the spores are heated. This fact is an important problem relating to the practical sterilization in bacteriology and in the food industry. Hence voluminous data on the heat resistance of Clostridium botulinum and Clostridium porogenes in various kinds of foods or food juices have been published (Townsend et al., 1938; Reed et al., 1951; Reynolds et al., 1952). From these data, it can be easily pointed out that the resistance value of a strain in a food is larger than that in phosphate buffer, whereas in another food the resistance value of the same strain is smaller than that in neutral phosphate buffer. Although the pH of the heating media has a marked influence on the thermal death rate of bacteria, it appears that the cause of such a difference in resistance values of a strain cannot be attributed wholly to the variation of pH values of the foods (Sognefest et al., 1948). In fact, there are evidences that some of the ingredients of food might exert a protective effect or a death accelerating effect for the organism during the heating. Weiss (1921) reported that the longer survival time was obtained when the spores of C. botulinum were suspended and heated in the foods with the higher sugar concentration. The similar protective effect of sugars on the bacterial spores has been demonstrated by Anderson et al. (1949) and Sugiyama (1951). Murray and Headlee (1931) found that the presence of peptone in the heating medium had shown sometimes a protective effect for the spores of C. tetani. Recently, Kawai and Tanaka (1952) have shown that several kinds of higher molecular substances, such as gelatin, starch, gum arabic, and alginic acid, have the protective effects for the spores of Bacillus mesentericus and Bacillus brevis. The test organisms used by these workers are relatively less resistant than the most resistant food spoilage bacteria, and the kinds of the substances tested on each strain are rather limited. Thus it seemed important to study the effects of various substances on the most resistant strain. Using the spores of Cameron's putrefactive anaerobe 3679 (Clostridium sporogenes, ATCC 7955), the effects of various carbohydrates, proteins, and bacterial cells were studied. In the previous papers Amaha (1952a,b, 1953) has clearly indicated that the thermal death time of spores of certain strains is influenced markedly by the nature of the recovery media. In general the more favorable was the nature of a medium for the development of heated spores, the longer was the survival time. Hence, it should be considered that the substances added in the basal heating medium have the two stages in their action to the spores; the first, during the heating time, and the second, after the substances were transferred in the subculture medium. In this paper an attempt was made to distinguish the two effects, i.e., the first effect, a true protection, and the second effect, a false protection, of each of substances tested.
Thermal Death-Point
Anaerobic respiration.-Inasmuch as PALLADIN and KOSTYTSCHEW, working independently, had agreed, contrary to the conclusions of several other observers, that anaerobic respiration was not identical with alcoholic fermentation, it seemed good to them to reinvestigate the question. They now finds that while not identical in all plants and under all conditions, there are striking coincidences. For example, in living lupine seeds and seedlings they consider the anaerobic respiration identical with alcoholic fermentation; but in frozen lupine seedlings and stem tips of Vicia Faba the former has nothing to do with the latter. In pea seeds and wheat embryos, living and frozen, there occurs a considerable formation of alcohol, and the anaerobic respiration is "in great part" alcoholic fermentation. They confirm the results of GODLEWSKI, STOCKLASA, and others regarding the presence of "zymase," but think it yet remains to be shown that it is identical with yeast zymase. Under certain conditions aceton and its allies are formed, both in aerobic and anaerobic respiration of living and frozen plants. It becomes more and more evident that the course of the respiratory decomposition of the protoplasm may be varied.-C. R. B.
Antibiotic Activity of the Fatty-Acid-like Constituents of Wheat Bran
An appreciable part of the antibiotic activity observed in connection with the culturing of an unidentified microorganism on a medium consisting principally of wheat bran and asparagus juice was found to reside in the medium itself. Investigation disclosed that the wheat bran was the source of this activity. Wheat bran has frequently been used as an ingredient in media assayed for antibiotic activity. Because of the possibility of confusing the antibiotic activity naturally present in wheat bran with the activity produced by microorganisms grown on media containing wheat bran, efforts were made to characterize the active factor involved. A hypothesis is presented that antibiotic activity may be formed by the hydrolysis and saponification (by the action of the microorganisms) of fatty constituents contained in the original substrates.