ALBERT STAIN

 Albert stain is usually done to visualize metachromatic granules or volutin present in bacteria's such as Corynebacterium diphtheriae.

REAGENTS :

Toluidine blue-malachite green stain (Albert stain)

Albert's Iodine

PRINCIPLE :

Toluidine blue and malachite green are cationic dyes. Volutin granules are stained by acidified basic dyes. Albert stain is acidified using addition of acetic acid and adjusted to pH 2.8. Here toluidine blue preferentially stain the granules whereas malachite green stains the cytoplasm of the cell. It is then fixed by albert's iodine.  

PROCEDURE :

• Make smear using the sample and heat fix the smear (or chemical fixation)
• Flood the slide using Toluidine blue-malachite green stain for 3-5 mins.
• Wash the slide using tap water or sterile water and blot dry it.
• Add Albert's iodine for 1 min and wash off the slide.
• Air dry and observe under 40x followed by oil immersion(100x).

OBSERVATION :

Bacterial cells - appears pale Green color arranged in cuneiform pattern.

Metachromatic granules -  appears Bluish-black.

References :

1. Apurba sastry essentials of medical microbiology - 2nd edn.

2. Wikipedia.