BIOL240L Study Guide - Quiz Guide: Gram Staining, Mycobacterium, Gram-Positive Bacteria
2 Oct 2017
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Red organisms (acid fast positive) : stained by carbolfuchsin, acid fast organism. Kinyoun modification: cold stain, carbolfuchsin and phenol concentration increased and non acid fast detergent added so that heating is not necessary. Bacillus mageterium: acid fast negative, stained dark blue, chains of rods. Mycobacterium phlei: acid fast positive, stained dark pink, clusters of round cells (streptobacillus) (staphylococcus) Central, terminal, and sub-terminal are where a spore can be located. Method: place drop of water on slide and remove loopful of bacteria from slant agar, suspend in drop of water. air dry and heat fix by passing through twice as many times as normal (6-8). 20 sec with safranin. wash, blot dry. decolorized. Results: bacillus cereus are white, outlined in grey background (thin streams of rods) Cells are not stained because the blackish colloidal particles of nigrosin do not penetrate. Some bacteria have a capsule surrounding their cell wall, made of mucilaginous substance (made of polysaccharides, carbs, polypeptides).
