| 摘要 |
PURPOSE:The medium for the beta-galactosidase test, enabling the determination on the same day as well as on the next day, and composed of yeast extract, casein- trypsin hydrolysis peptone, lactose, a specific alkali metal salt and a color- development substrate. CONSTITUTION:The medium is composed of 0.3-3g of yeast extract, 1-10g of casein-trypsin hydrolysis peptone, 0.05-0.5g of lactose, 0.5-5g of a dialkali metal hydrogen phosphate, 0.05-0.5g of an alkali metal dihydrogen phosphate and 0.5-5g of o-nitrophenyl-beta-D-galactopyranoside, and exhibits 7.2-7.7pH when dissolved in 1l of water. The above compositional ratio is critical, and especially, the amounts of the dialkali metal hydrogen phosphate and the alkali metal dihydrogen phosphate are set so as to give a pH of 7.2-7.7, preferably 7.4-7.6 since the beta-galactosidase reaction is suppressed in acidic state and exhibits pseudo-positive nature in alkaline state.
|
