Middleton J L, Marth E H, Fennema O
Appl Microbiol. 1975 Feb;29(2):195-200. doi: 10.1128/am.29.2.195-200.1975.
Saccharomyces cerevisiae was incubated in aerosol cans containing YM broth and dichlorofluoromethane (f-21). The presence and number of viable cells were determined by inoculating (1% vol/vol) YM broth and by the plate count procedure (YM agar). Inactivation of the yeast was greater or more rapid when: (i) the thermodynamic activity (saturation value) of f-21 became greater through increasing the concentration of chemical from 0.5 to 1.5% (wt/wt) in a given volume (20, 40, or 80 ml) of broth, or by holding the concentration of chemical constant but increasing the volume of broth in the test vessel, (ii) the temperature of treatment was increased (7, 22, 37, and 47 C), (iii) samples with 1.5% (wt/wt) f-21 were agitated, (iv) young (8 h) rather than old (36 h or 10 days) cells were treated, and (v) cells were grown in YM broth without, rather than with, glucose. Adjusting the pH (6.3 to 4.0) of broth before treatment, pretreating the substrate with f-21, or distilling the chemical before use had no effect on viability of cells when treated with f-21. Yeast cells inactivated by f-21, chlorine, or heat were more resistant to disruption by sonic treatment than were viable cells.
将酿酒酵母置于装有酵母麦芽汁肉汤（YM肉汤）和二氯氟甲烷（F - 21）的气雾罐中进行培养。通过接种（1%体积/体积）YM肉汤并采用平板计数法（YM琼脂）来确定活细胞的存在及数量。当出现以下情况时，酵母的失活程度更高或更快：（i）在给定体积（20、40或80毫升）的肉汤中，通过将化学物质的浓度从0.5%（重量/重量）提高到1.5%（重量/重量），或在保持化学物质浓度不变的情况下增加测试容器中肉汤的体积，使得F - 21的热力学活性（饱和值）增大；（ii）处理温度升高（7、22、37和47℃）；（iii）对含有1.5%（重量/重量）F - 21的样品进行搅拌；（iv）处理的是年轻（8小时）而非年老（36小时或10天）的细胞；（v）细胞在不含葡萄糖而非含有葡萄糖的YM肉汤中生长。在处理前调节肉汤的pH值（从6.3到4.0）、用F - 21预处理底物或在使用前蒸馏该化学物质，在用F - 21处理细胞时对细胞活力均无影响。与活细胞相比，被F - 21、氯或热灭活的酵母细胞对超声处理的抵抗力更强。
