Bioassay of pollution gas by metabolic heat measurement of yeast

利用微量量热计，以生长热图（代谢热培养时间曲线）的形式检测酵母培养物在30℃孵育过程中产生的热量。热演化曲线与细胞数和培养物浊度有很好的相关性。本研究研究了开放体系中高压气体对酵母生长曲线的影响，并利用Biothermo Analyzer定量分析了氮气、空气、氧气、氧化亚氮、氩气和氪气对酵母生长的抑制作用。利用生长热图估计了酵母在压缩气体下的微生物活性，并确定了50%抑制压力（ip50）和最小抑制压力（MIP），作为溶解气体毒性的指标。结果表明，压力的增加对酵母细胞有明显的抑制作用，抑制作用的顺序为O_2>N_2O>空气>Kr>N_2> ar氧。这些结果可应用于NH_3、Cl_2、NOx、SOx等各种有毒环境污染气体的生物测定。生物测定法是利用生物材料、微生物、植物、鱼类、贝类和哺乳动物来确定有毒化学物质数量的方法。近年来，该方法在环境污染评价领域得到了广泛应用，但由于气体在水中的溶解度较低，特别是在微生物作为生物材料的情况下，气体材料往往不能用于环境污染评价。该方法解决了上述问题，可用于气体的生物测定。

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.