B. Schaarschmidt

Microcalorimetric investigations of the metabolism of yeasts. Growth in chemostat cultures on glucose

SummaryThe growth of yeast cells on glucose in chemostat cultures at dilution rates of up to 0.4 h−1, was investigated using a fermentor linked to a flow microcalorimeter. The weight specific rates of heat production and oxygen consumption showed a linear dependence on the dilution rate but diverged for higher rates due to glucose repression and wash out of the culture. With the media used, it was possible to almost completely determine the energy balance; the biomass formed contained about 60% of the produced energy and 40% was accounted for by heat production.

Some like it hot calorimetric investigations of voodoo lilies

Abstract An isoperibolic calorimeter of approximately 3 liters volume and a sensitivity of 52.8 mV W is described, specially designed for studies on whole plants. It was used to monitor thermogenesis during anthesis (flowering up) of the voodoo lily, Sauromatum guttatum, a member of the family of Araceae. Simultaneous measurements of oxygen consumption indicate a high ratio of heat production to oxygen consumption and a strong uncoupling of oxydative phosphorylation during anthesis. Thermographic registration and temperature determinations along the whole plant show an elevation of the appendix temperature of 7°C above the surrounding.

Calorimetric investigations of pollution by xenobiotics

Abstract Parts of a forest ecosystem (decayed matter, soil and small animals) were investigated calorimetrically for the influence of a typical organic pollutant. Pentachlorophenol (PCP), a ubiquitously applied pesticide, was chosen as a representative man-made xenobiotic. At all concentrations used, PCP produced a pronounced stimulation of the energy metabolism by up to 350%.

Microcalorimetric investigations of the metabolism of yeasts. growth in batch and chemostat cultures on ethanol medium

SummaryThe heat evolution of aerobic batch and chemostat cultures of growing yeast (Saccharomyces cerevisiae), in ethanol medium was investigated with a flowmicrocalorimeter. A balance for energy, carbon and oxygen was established in the chemostat cultures. Acetate which was presumably formed during the degradation of ethanol accounted for about 24% of the energy content of ethanol, but was not metabolized. Furthermore, only 45% the energy produced was stored in cell material, whereas 55% appeared as heat. From this and from the carbon balance it is concluded that the production of yeast cell material from ethanol is an exothermic process.

Heat production in oscillating chemical reactions: three examples

Abstract Microcalorimetric measurements are reported for the metal-ion catalyzed Belousov-Zhabotinskii and the Briggs-Rauscher reactions as well as for the uncatalyzed reaction of phenol, bromate, and sulfuric acid. The rate of heat production and either optical or potentiometric signals are recorded simultaneously.

Simultaneous measurements of heat production and optical density in oscillating reactions

Abstract A device is presented which can be inserted into a calorimetric vessel to enable a simultaneous measurement of optical density and heat production. It consists mainly of a quartz rod and a photodiode which is sensitive from the near ultraviolet to the infrared. Specific wavelengths are selected by glass or interference filters placed between the light source and the rod. Homogeneity of the medium in the vessel can be achieved by a gentle but effective pneumatic stirring. The applicability of the whole set-up is demonstrated for two oscillating chemical reactions (Belousov-Zhabotinskii and Briggs-Rauscher reactions) and for the oscillating glycolysis of a cell-free cytoplasmic extract from yeast.

Pentachlorophenol - an environmental pollutant: Microcalorimetric investigations of an ecological model system

Abstract The influence of pentachlorophenol (PCP) on components of an ecological system was determined calorimetrically. After exposure to PCP at concentrations up to 0.4 g/l there was a significant stimulation to as great as 400 % of the rate of heat production in litter, soil and earthworms as a typical animal for this biotope. Even with the highest concentrations used no inhibitory effects could be detected in the present investigation.

Microcalorimetric study of yeast growth, utilization of different carbohydrates☆

Abstract The anaerobic growth of the yeast Saccharomyces cerevisiae on six different mono- and disaccharides was investigated calorimetrically. From the thermograms the kinetic data for the sugar uptake were determined. This methods holds for biphasic growth (diauxy) on mixed sugars too.

Microcalorimetric investigations of the growth of yeast. Energy balance of batch and continuous cultures.

Abstract Growth of yeast cells ( Saccharomyces cerevisiae ) at the expense of glucose or ethanol in batch and chemostat cultures was studied by flow-microcalorimetry. With glucose media and with batch cultures on ethanol the energy balances were completely established, whereas as with chemostat cultures on ethanol a lack of about 25% of the energy-input occured which was not converted into biomass or dissipated as heat.

Cadmium induced changes of the metabolic activity of the freshwater snailPlanorbis corneus estimated by direct calorimetry

By use of f1ow-microcalorimetric studies the effect of cadmium in the sublethal concentration range (0.5-h LC5 0 is 1.69 mg/l) on the metabolic activity of the freshwater snailPlanorbis corneus was revealed. The high toxicity was confirmed by the change in the heat production rate (mean value is 453 μW/g fresh weigth) in a cadmium perfusate down to a concentration of 0.01 μg/l. The decrease in heat output depended on the cadmium concentration and amounted from 19% at 0.01 μg/l to 88% at 1000 μg/l. The microcalorimetric method proved to be a useful continuous-f1ow technique to assess qualitatively and quantitatively the toxic effects of cadmium on an aquatic organism already 4 hours after exposure.ZusammenfassungMit Hilfe der Flow-Mikrokal orimetrie wurde die Uirkung von Cadmiumchlorid im subletalen Konzentrationsbereich auf die Stoffwechselaktivitat der SüβwasserschneckeP1anorbis corneus untersucht. Die Wärmeproduktion der Tiere sank im Mittel von 435μW/g Frischgewicht bei einer Cadmiumkonzentrat i on von 0.01 μg/l auf 81Z und bei 1000 μg/1 auf 19Z. Die Kalorimetrie eruies sich als eine nützliche Flow-Technik, mit der die Toxizität von Cadmium qualitativ und quantitativ bereits 4 Stunden nach der Exposition erfaβt werden kann.РезюмеС помощью микрокалор иметра с тепловым пот оком оцене