Staining

Bacterial Smear

First step in staining procedure, put a small amount of water on a slide along with some culture and allow to dry, then fix with methanol or heat

Positive Staining Technique

Staining procedure that uses a basic dye, stains the cell itself

Negative Staining Technique

Staining procedure that uses an acidic dye, stains the background dark, uses live culture

Simple Stain

Staining procedure in which only one stain is used

Differential Stain

Staining procedure that uses more than one stain

Gram Stain

Stain that determines whether or not a cell has peptidoglycan in the cell wall (gram negative vs positive), is a positively charged, differential stain

Primary Stain

First step in staining, binds to the cell feature of interest (positive)

Mordant

Second step in staining, chemically fixes the primary stain to the cell feature of interest

Decolorizer

Third step in staining, removes the primary stain from cells that lack the feature of interest

Secondary Stain

Fourth step in staining, stains the decolorized cells (negative)

Crystal Violet

Primary stain in gram staining, flood for 20 seconds

Gram’s Iodine

Mordant in gram staining, flood for 1 minute

Ethanol

Decolorizer in gram staining, allow to run off slide and rinse immediately

Safranin

Secondary stain in gram staining, flood for 1 minute

Bibulous Paper

Tool used to dab off excess stain after you finish staining procedures

Endospore Stain

Differential stain used to detect if a bacterial cell produced spores, must use steam to allow stains to penetrate the cells

Malachite Green

Primary stain for endospore staining, flood for 5-6 minutes

Heat

Mordant for endospore and acid-fast stains

Water

Decolorizer for endospore stains, rinse for 30 seconds

Safranin

Secondary stain for endospore stains, flood for 60 seconds

Acid-Fast Stain

Differential staining procedure that distinguishes bacteria based on the presence of mycolic acid in the cell wall

Cabolfuchsin

Primary stain for acid-fast stain, flood for 3-5 minutes

Acid Alcohol

Decolorizer for acid-fast stain, allow it to run off the slide and rinse immediatley

Methylene Blue

Secondary stain for acid-fast stain, flood for 2 minutes

Nigrosin

Stain used during negative stain