Lauryl Tryptose Agar

Lauryl Tryptose Broth is a selective medium for the detection of coliforms in water and wastewater.
This formulation is based on the Mallmann and Darby formulation. (1)
The tryptone provides the required carbon, nitrogen and vitamins in this medium.
Lactose is a fermentable carbohydrate.
The sodium chloride maintains the osmotic balance whilst the dipotassium hydrogen phosphate and potassium hydrogen phosphate act as buffers.
Sodium lauryl sulphate is a selective again used to inhibit non-coliforms.

References
(1) Mallmann, W. L. and Darby, C. W. 1941. Uses of a lauryl sulphate tryptose broth for the detection of coliform organisms. Am J. Public Health. 31:127

Additional Information

Shelf Life (days)	1095 days
Dehydrated Medium Appearance	Fine Powder
Dehydrated Medium Colour	Straw
Dehydrated PH	6.8 ± 0.2
Prepared Medium Appearance	Semi-solid gel
Prepared Medium Colour	Dark Straw
Prepared PH	6.8 ± 0.2
Storage	Once opened keep powdered medium closed to avoid hydration and use before the expiry date on the label.
Container	500G, 5KG, 10KG

Product Description

Organisms	Ref. No	Result
Escherichia coli	NCTC 12241	Growth with gas production
Enterococcus faecalis	NCTC 12697	Inhibited

Recommended incubation: Aerobically at 37 ± 1°C for 18 -48 hours.

Formula*

	g/L
Tryptone	20.0
Lactose	5.0
Sodium chloride	5.0
Dipotassium hydrogen phosphate	2.75
Potassium dihydrogen phosphate	2.75
Sodium lauryl sulphate	0.1


Total	35.6
*Adjusted/supplemented as required to meet performance requirements

Preparation

Suspend 35.6g of the medium in one litre of deionised / purified water.
Allow the medium to soak whilst mixing for 10 minutes.
Dispense into appropriate containers with fermentation tubes (Durham).
Sterilise at 121°C for 15 minutes.

Lauryl Tryptose Agar