This is to ensure you will be working with a bacterial culture instead of a fungal isolate.Ĥ. Show an instructor your isolated single test plate isolate and the slide of the simple stain of the specimen you have chosen. Attempt a simple stain of your candidate test plate isolate as described in part B of Exercise II. Check your "test plates" from Lab1: Exercise I, part D (ubiquity of microorganisms) for isolated single colonies to be candidates for your test plate isolate.Ģ. Record your observations on the report sheets.ġ. Examine under the microscope using first the 10X and then the 100X oil-immersion objective.Ħ. Remove excess water from the slide by touching one corner of the slide to the blotting paper, then place the slide between clean sheets of paper in the blotting pad and blot dry. Now, rinse the remaining dye off with a gentle stream of water from a faucet or wash bottle.Ĥ. Tilt the slide to allow the stain to drain off. *Avoid getting stain on your clothes, books, and fingers. Stain by covering the smear completely with methylene blue. Basic stains, having a positive charge, bind strongly to negatively charged cell components such as bacterial nucleic acids and cell walls.ġ. The single dye used here is methylene blue, a basic stain. In a simple stain, a bacterial smear is stained with a solution of a single dye that stains all cells the same color without differentiation of cell types or structures. The purpose of staining is to increase the contrast between the organisms and the background so that they are more readily seen in the light microscope. Living bacteria are almost colorless, and do not present sufficient contrast with the water in which they are suspended to be clearly visible. After cooling the specimen is ready for the simple stain. ![]() Instead, heat-fix the slide for a shorter period of time next time, then test.Ĥ. Chances are, your suspicions are correct, and you will burn your hand with the hot glass. If you think you have heated the slide too much, do not touch the slide to your hand to find out. The slide should be warm to the touch, not hot. Killing the cells with heat fixation also increases their permeability to the dyes used in staining.ĭo not under-fix (the smear will wash off) nor over-heat (the cells will be ruptured or distorted) your specimen. Its purpose is to bind the specimen to the slide so that it does not wash off during staining. This process is called heat fixing the specimen to the slide. Put the sample side facing up and label with your initials on one end of the slide. Next, heat fix the slide by placing it on the slide warmer for 5 minutes. Micrococcus luteus, and Saccharomyces cerevisiae.ģ. Prepare three separate smears, one each of Bacillus megaterium. Spread the drop over a small portion of the slide to make a thin film with lightly visible turbidity.Ģ. Next, with a sterile loop transfer a SMALL AMOUNT of the growth to the drop of water and rub the loop around until the material is as evenly distributed as possible to form a just visibly turbid suspension. Preparations of bacteria for staining can be made from growth on an agar plate or from a broth culture.ġ. To prepare a slide from cells grown on an agar medium, first place a SMALL drop, a loopful works well, of water on a clean grease-free slide. Preparation of a Bacterial Smear for Staining Review Lab procedures for operating a Brightfield Light microscopeī. Image 1: Heat Fixing over a bunsen burnerĪ.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |