Rapidly test for viability of probiotics with fluorescence.The number of probiotic-containing products on the market is increasing. Maintaining the viability of probiotic pro·bi·ot·ic n. A dietary supplement containing live bacteria or yeast that supplements normal gastrointestinal flora, given especially after depletion of flora caused by infection or ingestion of an antibiotic drug. bacteria in products is important, as is the ability to enumerate To count or list one by one. For example, an enumerated data type defines a list of all possible values for a variable, and no other value can then be placed into it. See device enumeration and ENUM. viable cells present in probiotic foods and drinks. Scientists at VTT VTT Technical Research Centre of Finland VTT Valtion Teknillinen Tutkimuskeskus (Finnish: Technical Research Centre of Finland) VTT Vélo Tout Terrain (French: mountain bike; aka ATB or MTB) Biotechnology and Food Research (PO Box 1500, FIN-02044 VTT, Finland) have tested fluorescence techniques as direct, rapid methods for evaluating the viability of probiotic bacteria both in pure cultures and in products. Suitable fluorescence staining techniques must be elaborated for each strain of the many probiotic bacterial strains used in products. The fluorescence probes used in examining probiotic viability are fluorochromes designed to express membrane integrity, membrane potential membrane potential n. The potential inside a cell membrane measured relative to the fluid just outside; it is negative under resting conditions and becomes positive during an action potential. or the enzyme activity Enzyme activity A measure of the ability of an enzyme to catalyze a specific reaction. Mentioned in: Glucose-6-Phosphate Dehydrogenase Deficiency of the cell. Scientists use a flow cytometer and an epifluorescence microscope with a digital image analyzer to visualize and differentiate the viable and nonviable nonviable /non·vi·a·ble/ (-vi´ah-b'l) not capable of living. non·vi·a·ble adj. Not capable of living or developing independently. Used especially of an embryo or fetus. probiotic bacterial cells in pure cultures and products. VTT researchers have been testing fluorescence techniques on probiotic bacteria in drinks and pharmaceuticals available in Finland. Pretreating the samples and the choice of fluorescence probe, staining buffer, incubation time and temperature are all important when staining different probiotic strains and products. Colorless fluorogenic substrates, which are converted into fluorescent products by esterases inside cells, have the advantage over other dyes in giving only a little background fluorescence. This is important when testing food supplies that contain particulate matter. Food ingredients strongly interfere with measurements in the samples stained with nucleic acid nucleic acid, any of a group of organic substances found in the chromosomes of living cells and viruses that play a central role in the storage and replication of hereditary information and in the expression of this information through protein synthesis. probes. The number of viable cells in pure cultures and probiotic juices, as analyzed by fluorescence microscopy and flow cytometry, correlates well with the results obtained by the traditional plate count method. The time needed for fluorescence microscopy and flow cytometry analysis is only 1 hr to 2 hr. This makes fluorescence techniques for measuring viable and nonviable probiotic cells a rapid and direct technique for evaluating the quality of probiotic cultures and products. Further information. Liisa Nohynek; phone: +358-9-456 5170; fax: +358-9-455 2103; email: liisa.nohynek@vtt.fi. |
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