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Name: Diane
Class code: DT420
Date: 06.11.2013
Microbiology report
Gram stain
Objectives: The aim of this experiment was to be able to stain bacteria correctly and be able to see it under the light microscope. In 1883 Hans Christian Gram discovered an important staining method that is used extensively today. The stain is called the Gram Stain. This experiment was done in order to differentiate microbes into two basic groups: Gram positive microbes and Gram negative microbes. The purpose of this experiment was to learn the gram staining method and to observe the characteristics of gram negative and gram positive microorganisms.
Materials: Microscope, Bunsen burner, glass slide pipette, loop, distilled water, nutrient agar of Escherichia coli, nutrient agar of Staphylococcus aureus, crystal violet, gram iodine, ethanol, safranine, oil immersion, a piece of napkin , holder.
Method: As per manual. Bacteria stained- Escherichia coli and Staphylococcus aureus.
Results:
Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining. Safranin is added after the crystal violet, coloring all gram-negative bacteria with a red or pink color. Escherichia coli became pink when looking under microscope, this meant it was gram-negative. Staphylococcus aureus stayed purple and it mean it was gram-positive. Escherichia coli was rod shaped, whereas Staphylococcus aureus look more round shape.
Discussion: The results I got were expected because safranin is used to visualize the otherwise colorless gram-negative bacteria whose much thinner peptidoglycan layer does not retain crystal violet. Stains and dyes are widely used in the scientific field to highlight the structure of the biological specimens, cells, tissues etc. Gram-positive bacteria have a thick mesh-like cell wall which is made up of peptidoglycan (50-90% of cell wall), which
Class code: DT420
Date: 06.11.2013
Microbiology report
Gram stain
Objectives: The aim of this experiment was to be able to stain bacteria correctly and be able to see it under the light microscope. In 1883 Hans Christian Gram discovered an important staining method that is used extensively today. The stain is called the Gram Stain. This experiment was done in order to differentiate microbes into two basic groups: Gram positive microbes and Gram negative microbes. The purpose of this experiment was to learn the gram staining method and to observe the characteristics of gram negative and gram positive microorganisms.
Materials: Microscope, Bunsen burner, glass slide pipette, loop, distilled water, nutrient agar of Escherichia coli, nutrient agar of Staphylococcus aureus, crystal violet, gram iodine, ethanol, safranine, oil immersion, a piece of napkin , holder.
Method: As per manual. Bacteria stained- Escherichia coli and Staphylococcus aureus.
Results:
Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining. Safranin is added after the crystal violet, coloring all gram-negative bacteria with a red or pink color. Escherichia coli became pink when looking under microscope, this meant it was gram-negative. Staphylococcus aureus stayed purple and it mean it was gram-positive. Escherichia coli was rod shaped, whereas Staphylococcus aureus look more round shape.
Discussion: The results I got were expected because safranin is used to visualize the otherwise colorless gram-negative bacteria whose much thinner peptidoglycan layer does not retain crystal violet. Stains and dyes are widely used in the scientific field to highlight the structure of the biological specimens, cells, tissues etc. Gram-positive bacteria have a thick mesh-like cell wall which is made up of peptidoglycan (50-90% of cell wall), which