Measurement of heat evolution and correlation with oxygen consumption during microbial growth (Reprinted from Biotechnology and Bioengineering, vol 11, pg 269, 1968)

A procedure for measuring the rate of heat production from a fermentation h as been developed. The method is based on measuring the rate of temperature rise of the fermentation broth resulting from metabolism, when the tempera ture controller is turned off. The heat accumulation measured in this manne r is then corrected for heat losses and gains. A sensitive thermistor is us ed to follow the temperature rise with time. This procedure is shown to be as accurate as previous methods but much simpler in execution. Using this t echnique, the rate of heat production during metabolism was found to correl ate with the rate of oxygen consumption. Experiments were performed using b acteria (E. coli and B. subtilis), a yeast (C. intermedia), and a mold (A. niger). The substrates investigated included glucose, molasses, and soy bea n meal. The proportionality constant for the correlation is independent of the growth rate, slightly dependent on the substrate, and possibly dependen t on the type of organism growth. This correlation has considerable potenti al for predicting heat evolution from the metabolism of microorganisms on s imple or complex substrates and providing quantitative parameters necessary for heat removal calculations.