Endo Les Agar Base 1137 Condalab

Endo LES Agar Base is a modification of Endo Agar Base (Cat. CL-1118), for testing water by the membrane filter technique. It uses Lauryl Sulphate Broth (Cat.CL- 1310) as an enrichment to obtain greater growth. LES stands for Lawrence Experimental Station which is a standard formula for testing waters and is also specified in the coliform’s fermentation technique.

Like Endo Agar, it uses fuchsin to differentiate between positive lactose-fermenting and lactose non-fermenting bacteria. Acetaldehyde production by lactose fermenting organisms such as Escherichia coli produce characteristic red colonies and a red surrounding area, marked by its reaction with Sodium sulphite in the presence of fuchsin. Lactose non-fermenters form colourless, transparent colonies.

Casein and Meat peptones, and Tryptose provide nitrogen, vitamins, minerals, and amino acids that are essential for growth. Yeast extract is a source of vitamins, particularly of the B-group and lactose is the fermentable carbohydrate providing carbon and energy. Potassium phosphates act as a buffer system. Sodium deoxycholate inhibit growth of gram-positive bacteria. Sodium lauryl sulphate partially inhibits organisms other than coliforms. Sodium chloride supplies essential electrolytes for transport and osmotic balance and bacteriological agar is the solidifying agent.

Note: Basic fuchsin is a potential carcinogen and precautions should be taken to avoid inhalation of the dye powder as well as contact with skin.