The process of adding a dye to a bacterial culture STAINING The process of adding a dye to a bacterial culture

Dyes Basic dye—possess a positive charge Acidic dye—possess a negative charge Remember, bacteria posses a slight negative charge on their surface

SIMPLE STAINING Use only one dye For the purpose of viewing bacterial shapes and arrangements Simple Stain the following: 1) E. coli 2) S. aureus 3) A colony from the “Microbes in the Environment” plate

3 Types of Staining Procedures Simple Staining (shapes and arrangements) Differential Staining (Gram reactions) Special Staining (Capsule, flagella, spores)

PROCEDURE: Prepare smear of bacterium Air dry Heat fix the bacteria to the slide (release of “sticky” proteins from the cell surface of the bacteria adheres the bacterial cell to the slide) Apply crystal violet to the smear; let stand 45 seconds

Procedure Cont. Rinse with distilled water or tap water Blot dry with bibulous paper View using microscope

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Methylene blue Crystal Violet Fuchsin Simple stains allow visualization of Shapes Arrangements Proteus vulgaris Staphyloccocus aureus Bacillus cereus Page 55

Fracisella tularensis Causitive agent of Rabbit fever Methylene blue stain Sacharromyces cerevisiae (Brewer’s yeast) Methylene blue stain

Bacillus anthracis (anthrax) Gram positive Crystal violet stain Campylobacter jejuni (traveler’s diarrhea) Gram negative Fuchsin stain