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Applying a primary stain (crystal violet) to a heat-fixed smear of a bacterial culture. Heat fixation kills some bacteria but is mostly used to affix the bacteria to the slide so that they do not rinse out during the staining procedure. The addition of iodine, which binds to crystal violet and traps it in the cell
Once stained, they do not decolourize. The addition of heat during the staining process is a huge contributing factor. [15] Heat helps open the spore's membrane so the dye can enter. The main purpose of this stain is to show germination of bacterial spores.
The sample is then heat-fixed to the slide and stained with nuclear fast red for 15 minutes, then rinsed with deionized water. [8] Next, a green stain is applied for 10 seconds, then rinsed with ethanol. The slide is placed under a compound light microscope for sperm observation.
[40] [41] The Food and Drug Administration in the US (FDA) has determined that gentian violet has not been shown by adequate scientific data to be safe for use in animal feed. Use of gentian violet in animal feed causes the feed to be adulterated and is a violation of the Federal Food, Drug, and Cosmetic Act in the US. On June 28, 2007, the FDA ...
Using aseptic technique, prepare and air dried heat fixed slide with the desired organism. Prepare a boiling water bath. Cover the slide with a piece of paper towel and place on staining rack over the water bath. Flood the paper towel on the slide with Malachite Green (primary stain). Steam the slide for 5 to 7 minutes (mordant).
Food grading involves the inspection, assessment and sorting of various foods regarding quality, freshness, legal conformity and market value. [1] [2] Food grading is often done by hand, in which foods are assessed and sorted. [1] [2] Machinery is also used to grade foods, and may involve sorting products by size, shape and quality.
If an alcohol thermometer utilizes a combination of ethanol, toluene, and pentane, its lower temperature range may be extended to measure temperatures down to as low as −200 °C (−328 °F). [3] However, the measurement temperature range c. −200 °C to 78 °C, is highly dependent upon the type of alcohol used.
When looking at the smears for TB, it is stained using an acid-fast stain. These acid-fast organisms like Mycobacterium contain large amounts of lipid substances within their cell walls called mycolic acids. These acids resist staining by ordinary methods such as a Gram stain. [9] It can also be used to stain a few other bacteria, such as Nocardia.