Lab__3a_Identification_of_Unknown_Bacteria_-_Part_I

This technique spreads out original parent bacteria

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This technique spreads out original “parent bacteria” in a sparse pattern that ,after growth, results in individual colonies . After incubation, the 4 th quadrant of your plate should have dots. These small “dots” are individual colonies, and represent millions of bacteria of the same type. Isolation Streak Plates & Aseptic Technique * IMPORTANT!!!: Be very gentile when streaking the sample onto the plate. Try not to gouge the surface of the medium with your inoculation loop. From the Virtual Microbiology Classroom on ScienceProfOnline.com
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Differential Stains Most stains used in microbiology are differential. Differential stains involve use of more than one dye, so that certain differences between cell type or structures can be distinguished. Image: Acid fast stain, T. Port From the Virtual Microbiology Classroom on ScienceProfOnline.com
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Gram Stain Distinguishes between two large groups of microorganisms: - purple staining, Gram-positive cells - pink staining, Gram-negative cells These two types of cells differ significantly in the chemical and physical structure of their cell wall. The structure of the thinner cell walls of Gram negative bacteria cannot hold the dyes previously used, once the decolorizer is applied. + u - G To prepare Gram bacterial smear for staining next week: Draw three circles on slide using wax pen. Also include a “G” to identify that slide will be Gram stained. Flip slide over. Use DI water dropper to place very small drop of water inside each circle. Using a sterilized inoculation loop , take a small sample of your unknown. Be gentle! The bacteria is on the surface of the medium. Swirl into the water in the center circle of your slide. Q: Why are there two additional circles on our slide? Use same method to add controls to circle on left and right. Heat fix the slide on top of your microincinerator . Allow it to stay in the platform for 5 minutes after water has completely evaporated.
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