Patent ID: 8071326

Claim:
A method for detecting metabolic activity in viable yeast cells in industrial fermentation applications, comprising: (a) providing a sample containing yeast cells, (b) contacting said sample containing yeast cells with 1) a molecule or dye that is altered by metabolically active viable yeast cells into a detectably fluorescent form, wherein the molecule or dye comprises fluorescein diacetate or OREGON GREENâ„¢ (2â€²,7â€² difluorofluorescein), and 2) a compound that increases the rate of uptake of the molecule or dye into the yeast cells or speeds up the rate of conversion of the molecule or dye into a detectably fluorescent form inside said yeast cells; (c) detecting fluorescence of the molecule or dye that is altered into a detectably fluorescent form by the metabolically active viable yeast cells in said sample, wherein the detection is performed by a fluorometer; and (d) repeating step (c) over a time course, wherein a change in fluorescence over the time course indicates a change in metabolic activity of viable yeast cells.