The Influence of Temperature on the Rate of Growth of Saprophytic Actinomyces

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Abstract
Actinomyces occur commonly in commercial cold stores. They can be isolated from the walls but are obtained in greatest number from straw on the floor of the store. Measurements of the rate of growth of actinomyces from cold stores show that the majority of the strains studied have their optimum temperature at 37° C. They are capable of growth from 40° to 5° C., growth becoming infinitely slow at just above 0° C. One strain, however, had its optimum temperature for growth less sharply defined at 20°-30° C. and grew well, though slowly, at o°C. The curve obtained by plotting the “velocity constant of growth” against temperature suggests that growth becomes infinitely slow at about—5° C. Application of the Arrhenius equation to the results obtained is discussed. Comparison with certain strains isolated from soil, having their optimum temperature at 37° C., gave results analogous to those obtained with strains from cold stores, also having their optimum at 37° C. The significance of actinomyces in imparting “musty” flavours to stored foodstuffs is indicated.