BACTERIAL CALORIMETRY II. RELATIONSHIP OF HEAT PRODUCTION TO PHASES OF GROWTH OF BACTERIA

Abstract

Realizing the importance of establishing the time-relationships of a biological process, we have begun our investigations of bacterial calorimetry with experiments to determine the course of the production of heat during the growth of a culture of bacteria. At the points where the temperature was recorded we have counted the bacteria in the culture. From the results of these studies, which will be reported in this paper, we have been able to plot the curve of heat production with respect to time, discovering points of inflection of this curve, and have correlated the curves of heat production and of growth of pure cultures of several varieties of bacteria in different kinds of media. quantitative data were secured as to the number of bacteria present at each unit of time and the gram calories liberated by them. Measurements of the sizes of the bacteria, deterrminations of their surface area and chemical studies of their metabolism were not made at this time as it seemed wiser to postpone these for future investigations which will be facilitated by being based upon a knowledge of the relationship of the production of heat to the phases of the growth of microbrganisms. Little definite information on this subject could be gathered from the literature, as the physiologists who have done most of the work in this field have overlooked a number of the significant phases of bacterial growth. Curves of heat production with respect to time appear in many papers. But in most cases the 123