Improving sensitivity cf bio-luminescent assay of microbial cells - by first incubating to increase population or adenosine tri:phosphate content

摘要

The sensitivity is improved when the sample is incubated for a short time in a suitable nutrient medium. Incubation can be for 10-20 min. so as to activate metabolism and increase ATP content to the level found during the logarithmic growth phase. Alternatively incubation is for 2-16 hr (bacteria or yeast) or 0.5-5 days (slowly-growing bacteria or fungi) to increase cell number to a measurable level. Non-microbial ATP is destroyed by incubating in the presence of 0.02-0.5% nonionic surfactant e.g. an ethoxylated alkylphenol and of 0.001-0.5 units per ml of an ATPase. The method is used to examine hygienic status of e.g. water pharmaceuticals, body fluids, food, etc. The limitations of the normal ATP method as regards sensitivity, accuracy and interference by non-microbial ATP are avoided, and both measurement and incubation are carried out in the same cell, so transfer errors are eliminated. By using selective growth media, rapid identification of some species becomes possible.