BACTERIA CLASSIFICATION BY GRAM STAINING. Lab work.

THE AMERICAN UNIVERSITY IN CAIRO

BIOLOGY DEPARTMENT

SCIENCE 453 : BIOLOGY FOR ENGINEERS

REPORT No.1

BACTERIA CLASSIFICATION BY GRAM STAINING

Presented By : Karim A. Zaklama

92-1509

Sci. 453-01

24/2/96

Objective:

To test a sample of laboratory prepared bacteria and categorise it according to Christian's gram positive and gram negative classes and also by viewing it under a high powered microscope and oil immersions; classify its shape and note any special characteristics.

Introduction:

Bacteria was categorised into two groups in 1884 by the Danish Bacteriologist Christian, gram positive and gram negative by a staining technique where the ability to avoid de-coloration of Crystal Violet solution by alcohol would render the category of gram positive, and gram negative if the bacteria is de-coloured. This could be noted by the final colour of the bacteria: a violet colour where Gram positive and a pink colour of the Safranin added pending the de-colouring process.

English: Lab algorithm to determine the bacteria i...

Gram-positive anthrax bacteria with counterstained...

Gram-positive bacteria, stained purple, of both th...

Materials:

1. Bacteria Sample

2. Microscope Slide

3. Gram Staining Kit and Wash Bottles

a. Crystal Violet Solution

b. Iodine Solution

c. 95% Ethyl Alcohol

d. Safranin

e. Distilled Water

4. Bibulous Blotting Paper

5. Microscope

6. Oil

Procedure:

A. Preparation :

1. Bacteria is cultivated on agar jelly in an incubator at 25°C for 24 hours.

2. Obtain a microscope slide and with a toothpick, smear a thin coat of the bacteria sample onto the slide

3. Cover the smear with a drop Crystal Violet and leave standing for 20 seconds

4. Wash off the stain with distilled water; drain and blot off the excess with bibulous paper.

5. Apply Gram's Iodine on the smear and leave to stand for 1 minute.

6. Drain the excess iodine and apply 95% Ethyl alcohol for 20 second duration or till the alcohol runs clearly from the slide.

7. The smear...