| 摘要 |
A nutrient prepn. of constant composition for micro-biological culture media contg. a fermentable sugar consists of a powder form readily sol. lyophilisate whose main ingredient is an aq. extract of grain with addn. of mineral salts, and/or a gelling agent, another sugar, a vitamin and an antiseptic. Specific examples of lyophilisate starting materials are malt and beer worts giving lyophilysates with 50-70% maltose, and 15-30% dextrin. To these may be added 1-20% glucose 0.5-20% gelatine or gelose, and other addns. as above. The aq. extract mixture is cooled to -25 or -30 degrees C and the water removed by sublimation at 0.3-0.4 torr and the resulting lyophilisate further dried at 30-50 degrees/0.2-0.3 torr and stored in water- and moisture-proof packings. Apart from avoiding uncertainty of microbiological results due to variations in the medium arising from the effect of climatic fertilizer and seasonal factors, the use of these lyophilysates effects a considerable time saving in the prepn. of the culture media. |
