PRACTICAL MICROBIOLOGY
EXPERIMENT: GRAM STAINING TECHNIQUE
Lab experiment performing pictures with description.
THEORY:
The gram staining technique was discovered in 1884 by Danish
Bacteriologist Hans Christian Gram. It is based on the chemical
and physical properties of bacterial cell wall. Gram positive
bacteria have thick layer of peptidoglycan in their cell wall,
while gram negative have a thinner layer. The difference in the
cell wall composition allow the bacteria to be stained
differently.
• GRAM POSITIVE: Bacteria stain violet because the
peptidoglycan retain the crystal violet dye.
• GRAM NEGATIVE: Bacteria stain red or pink because the
thinner peptidoglycan layer doesn’t retain the crystal
violet dye.
PREPARATION: Sanitize the area by spraying ethanol and
cleaning with cotton/tissue.
, CHEMICALS:
Crystal violet stain, iodine, safranin stain, decolorizer.
EXPERIMENT: GRAM STAINING TECHNIQUE
Lab experiment performing pictures with description.
THEORY:
The gram staining technique was discovered in 1884 by Danish
Bacteriologist Hans Christian Gram. It is based on the chemical
and physical properties of bacterial cell wall. Gram positive
bacteria have thick layer of peptidoglycan in their cell wall,
while gram negative have a thinner layer. The difference in the
cell wall composition allow the bacteria to be stained
differently.
• GRAM POSITIVE: Bacteria stain violet because the
peptidoglycan retain the crystal violet dye.
• GRAM NEGATIVE: Bacteria stain red or pink because the
thinner peptidoglycan layer doesn’t retain the crystal
violet dye.
PREPARATION: Sanitize the area by spraying ethanol and
cleaning with cotton/tissue.
, CHEMICALS:
Crystal violet stain, iodine, safranin stain, decolorizer.
