This paper describes the temperature and population distribution in the nest hill of the wood ant Formica polyctena. Calorimetric and manometric data on the heat production of ants, pupae, and nest material were used to estimate their possible contribution to the heat balance of the nest hill. The pattern of isothermal lines in the nest did not fully correspond with the population distribution. Oxygen consumption and heat production of the worker ants and pupae steadily with arising ambient temperature. Investigations of the nest material showed a rapid increase in oxygen consumption in spring and a slower decrease in autumn. From spring to autumn the heat production of material from the center of the nest was higher than that of peripheral material. Heat production of the nest material originates in microbial activities and is chiefly the result of aerobic metabolism. The mass—specific heat production of ants is clearly higher than that of nest material. However, considering the total mass of the nest, the rate of heat production of the nest material is more than seven times the heat evolved by the ants. The seasonal fluctuation in the heat production of nest material coincides well with the active phase of the ants. It is conceivable that the nest materials is aerated and loosened by the building actions of the ants, and thus enough nutrient material and optimum conditions are available to the microorganisms.
A short survey is given on recent calorimetric studies of microbial growth, which raised the question whether calorimetrically obtained thermograms can be used for identification of different organisms. Advantages and the efficiency of the method are critically discussed.
The heat evolution of aerobic batch cultures of growing yeast (Saccharomyces cerevisiae) in glucose media was investigated by a combination of a flow-microcalorimeter with a fermentor vessel. The course of heat production, cell production and the rate of oxygen consumption were qualitatively the same for all glucose concentrations between 10 mM and 100 mM. Under optimal aerobic conditions a triphasic growth was observed due to the fermentation of glucose to ethanol, respiration of ethanol to CO2 and acetate, and respiration of acetate to CO2. Energy and carbon were found to be in balance for all glucose concentrations.
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