1. Lab 3 Staining

2. Staining Bacteria are colorless for the most part.
Staining makes bacteria more easily visible.
This means that the structures have to be contrasted from their environment so that they can be seen easily.
Stain is a dye used to color the living or dead organelles.

3. Staining
Simple staining : only one dye . Ex. Simple stain methylene blue
Differential staining: more than one dye . Differentiation among bacteria is possible Ex. Gram stain
Special staining: stain Special structures Ex. Capsule stain , spore stain.

4. Simple stain
Use only one dye
Ex. Methylene blue or safranin

5. Gram stain Hans Christian Gram , Danish scientist
Classify Bacteria into Gram negative & Gram positive .
Thin cell wall
Thick cell wall

6. 4 dyes 1- primary stain: ( crystal violet ) 1 minute
2- mordant : ( iodine ) 1 minute
3- decolorizer : ( alcohol or acetone ) 1-2 seconds
4- counterstain : ( safranin ) 1 minute

9. Smear preparation

10. common bacterial arrangement

11. Gram Positive Cocci

13. Nontypical Cell Walls
Several bacterial groups lack the cell wall structure of gram-positive or gram- negative bacteria, and some bacteria have no cell wall at all.
Mycobacterium and Nocardia thick, waxy nature cell wall
archaea (polysaccharides cell wall)
Mycoplasmas ( Does not have cell wall)

14. Cellular morphology and arrangement (Draw a detailed sketch)
Gram Stain
Observation and Interpretations
Record your observation in the chart below:
Organism or source
Cellular morphology and arrangement
(Draw a detailed sketch)
Color
Gram reaction (+/-)