New Brunswick Scientific has introduced a new device that automatically counts yeast cells in about 30 seconds, making manual counting obsolete. Like the original NuceloCounter, an automated device for counting mammalian cells, the new NucleoCounter YC-100 for yeast combines a fluorescence microscope with CCD camera and integrated image analysis software to perform rapid and accurate cell counts.
Monitoring the cell count during a fermentation run allows the scientist to activate inducible systems, or harvest at optimal times for the best product yield. The NucleoCounter YC- 100 can provide a fast and accurate DNA-based volumetric cell count within seconds, independent of debris or substrate aggregates in the media.
This system uses a disposable sampling device, the NucleoCassette. The small, plastic cassette is internally pre-coated with a fluorescent dye, propidium iodide (PI), which stains the cells' nuclei. Because the NucleoCounter detects signals from the stained nuclei, and not the cell, the system operates without regard to cell size or morphology.
MATERIALS AND METHODS
Withdraw 100 μL of culture to ensure a representative sample, and place 50 μL into a 1.5 mL tube. Mix thoroughly by inverting and shaking to ensure homogeneity. Treat with 450 μL of Reagent YC-100, a lysis/disaggregation buffer, which permeates the yeast cell wall and membranes, allowing the cellular DNA to be stained. Reagent YC-100 has the ability to dissociate minor clusters of yeast cells, but not to dissolve or dissociate cells that are in the process of reproductive division. Vortex or pipette vigorously for a few seconds to mix. The total volume is now 500 μL, with a 10-fold dilution. If necessary, repeat the dilution process to yield a sample 1 x 105 cells/mL to 2 x 106 cells/mL. (In gene