Members of the phyla Proteobacteria (exception: some members of the order Rickettsiales), Cyanobacteria and Spirochaetota. Members of the phyla Bacillota and Actinomycetota (exception: genus Mycobacterium). Remove the excess of fluid with a paper towel and allow to air dry until the specimen is completely dry. Slide Test Catalase Test: Positive and Negative results Transfer a small amount of bacterial colony to a surface of a clean, dry glass slide using a lo op or sterile wooden stick (be sure the colony is visible to the naked eye on the slide).Flood gently with acetone-ethanol solution. Typically, gram positive bacteria have thicker cell walls (approximately 40 layers of peptidoglycan) compared to Gram negative bacteria, which have only 1-2.Add Lugol's solution (which contains iodine), wait for 1 minute.Add chrystal violet, wait for 1 minute.Fix the specimen by moving the slide, with the preparation side up, 6-8 times through the burner flame.Disperse some colony material in a drop of NaCl, air dry (in the incubator, if necessary).Divide the slide with the help of the diamond pen.to the Gram stain, bacteria can be divided into two groups: Gram positive and Gram negative. Then a counterstaining with safranin or basic fuchsin is performed to stain gram negative bacteria pink or red. to stain tissues, cells, cell components, cell contents, or. When Gram-negative bacteria are treated with the decolourizing solution the outer membrane will be dissolved and the thin peptidoglycan exposed, so that the CV-I complex is washed out. When Gram-positive bacteria are treated with the decolourizing solution (ethanol-acetone), the bacteria will be dehydrated and the colour retained. Then iodine (I -) will be used to form a large complex (CV-I) with CV and thereby bind the stain to the bacterium. Crystal violet (CV +), which is the primary dye binds to the negatively charged groups on the bacteria and stain them purple. Gram negative bacteria have a much thinner cell wall and also an outer membrane. Gram-positive bacteria have a thick cell wall (peptidoglycan), which consists of several layers and can be likened to a network. If you viewed the slide microscopically after the crystal violet step, Gram-positive cells would appear in color while Gram-negative cells would appear in color. These two groups are gram positive and gram negative bacteria, which are stained purple and pink to red, respectively. Classification of bacteria Shyam Mishra 212.8K views. Gram positive bacteria Microbiology 18.4K views20 slides. Staining Techniques in Microbiology Guddeti Prashanth Kumar 322.4K views74 slides. Gram staining Shivang Patel 138.7K views14 slides. Gram staining is a so called differential staining techniques, since one can distinguish two major groups of bacteria by this method. Gram positive and gram negative bacteria Mohit Hinsu 4.4K views16 slides.
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