| Research Abstract |
Using a microcalorimeter the heat evolved during incubation of yeast cultures at 30℃ was detected in the form of growth thermogram (metabolic heat-incubation time curve). Correlation of the heat evolution curves with the number of cells and the turbidity of the culture was found to be very good. In this study, the effects of high-pressure gas in open system on the growth curve of yeast were investigated and the inhibitory action of the gases (nitrogen, air, oxygen, nitrous oxide, argon and krypton) on the growth was quantitatively assayed using a Biothermo Analyzer. The growth thermograms were used to estimate microbial activity of yeast under compressed gases and to determine the 50% inhibitory pressure (IP5O) and minimum inhibitory pressure (MIP) that is regarded as an index of toxic potency of dissolved gases. It was found that the increase of pressure induced clear inhibitory action on yeast cells, especially for The order of the action was as follows O_2>N_2O>air>Kr>N_2>Ar.oxygen.
These results can be applied for a bioassay of various toxic and environmental pollution gases such as NH_3, Cl_2, NOx and SOx. The bioassay is the method to determine the quantity of toxic chemicals using biological materials, microorganisms, plants, fishes, shellfish and mammals. Recently, this assay became to be often used in the field of assessment of environmental pollution, however, gas materials were out of this element, especially when microorganisms are used as biological materials, for the low solubilities of gases into water. The method we proposed settled these problems and can be used for the bioassay of gases.
|
