The temperature optimum of the intestinal flora of the rat

Abstract

Two types of experiments were performed to determine if the microbial flora of the intestinal tract of the rat was optimally adapted to body temperature. The first involved the preparation of agar-spread plates from dilutions of intestinal material and incubation at a variety of temperatures. The temperature optima of the colonies which arose were then determined by replica plating. The second procedure involved the measurement of the temperature optimum for the incorporation of radioactive isotopes into the mixed microbial flora taken directly from the intestinal tract and studied without culture or preincubation. One series of experiments involved measurement of the rate of incorporation of 32PO4≡ into ribonucleic acid and deoxyribonucleic acid. In another set of experiments, the temperature optimum for the incorporation of 14C-glucose into the mixed microbial flora was measured. All of these studies showed that the optimum temperature of the microbial flora was indeed similar to the temperature of the habitat. Preliminary studies were also done with a dog and with red squirrels, with similar results.