OPPapers.com

Bacteria Classification By Gram Staining

Bacteria Classification By Gram Staining


THE AMERICAN UNIVERSITY IN CAIRO
BIOLOGY DEPARTMENT
SCIENCE 453 : BIOLOGY FOR ENGINEERS REPORT No.1
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.

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 should rinsed for a few seconds with distilled water to
stop the action of the alcohol. 8. Drain and blot off the excess with bibulous
9. Introduce Safranin to...