Lab__3b_Identification_of_Unknown_Bacteria_-_Part_II

Bright pink staining acid fast cells af cell are

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- bright pink staining, Acid-fast cells (AF) Cell are considered to be Acid-fast if they have mycolic acid in their cell wall. Q: What is mycolic acid, and which types of bacteria have it? + u - A Create a smear of organism you are testing. Cover smear with a blotting paper. Saturate paper with Ziehl’s carbol fuchsin (say fyook-sin ). Heat 3 – 5 minutes. Remove blotting paper. Rinse slide with tap water, then decolorize the smear for 10 - 15 seconds with acid alcohol. Rinse. Apply crystal violet for 1 minute, wash, blot dry. ACID-FAST STAINING PROCEDURE Blotting paper Ziehls carbol fuchsin (3 – 5 min heat) > rinse Acid Alcohol (10 – 15 sec) > rinse crystal violet (1 min) > rinse & blot dry From the Virtual Microbiology Classroom on ScienceProfOnline.com Watch video of How to Do an Acid Fast Stain
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Endospore Stain Distinguishes between two things: - endospores, which stain green - vegetative cells, which stain pink Some bacteria produce endospores, dormant, highly-resistant structures that can survive environmental extremes (desiccation, heat, harmful chemicals). Most notable genera: Bacillus and Clostridium Endospores cannot be stained by normal staining procedures because their walls are practically impermeable. Endospore stain uses heat to drive the primary stain, (malachite green) into the endospore. After cooling, the sample is decolorized with water and counter stained with safranin. Results in green stained endospores and red-colored vegetative cells . + u - E ENDOSPORE STAINING PROCEDURE Malachite Green (5 min heat) > rinse Safrinin (1 min) > rinse & blot dry From the Virtual Microbiology Classroom on ScienceProfOnline.com Watch video of How to Do an Endospore Stain
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Dichotomous Key Simple Stain Cocci Bacilli Gram Stain Gram negative cocci Gram positive cocci Mannitol Salt yellow pink Staphylococcus aureus Staphylococcus epidermis Gram Stain Gram negative bacilli Gram positive bacilli MacConkey’s No color change Salmonella pullorum Pink colonies E. coli Enterobacter aerogenes Acid Fast stain Acid Fast Mycobacterium tuberculosis Not acid fast Endospore stain Forms endospores
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