LAURYL SULPHATE BROTH - 500 GRAMAS

Código: TM150 - Referência: LAURYL SULPHATE

SOLICITE SEU ORÇAMENTO

COMPARTILHAR:

 

For detection and enumeration of coliform bacteria

Composition

 

Ingredients

Gms/Ltr.

Tryptose

20.00

Lactose

5.00

Sodium chloride

5.00

Dipotassium phosphate

2.75

Mono potassium phosphate

2.75

Sodium lauryl sulphate

0.1

*  Dehydrated powder, hygroscopic in nature, store in a dry place, in tightly-sealed containers below 25°C and protect from direct Sunlight.

 

Instructions for Use

Dissolve 35.6gms in 1000ml distilled water. Gently heat to boiling with gentle swirling and dissolve the medium completely. Distribute 10 ml into each test tubes containing inverted Durham tubes. Sterilize by autoclaving at 15 psi (121°C) for 15 minutes. Cool to 45-50ºC prior to inoculation.

 

Appearance: Light yellow colour, clear to trace slightly hazy

pH (at 25°C): 6.8 ± 0.2

 

Principle

LAURYL SULPHATE BROTH is used for the detection and enumeration of coliform bacteria in water,  and food products. Lauryl sulphate broth promotes a rich growth and copious  gas  production  from  small inocula of coliform organisms. Aerobic sporing bacteria are completely inhibited. Tryptone  provides the nitrogen, carbon compounds, vitamins and amino acids. Lactose is the fermentable sugar. Sodium chloride maintains the osmotic balance of the medium. Dipotassium phosphate and Mono potassium phosphate controls the pH during fermentation of Lactose. Lactose-positive bacteria metabolize lactose with gas formation is indicated by using inverted Durham tubes. Incubate at the wished temperature for 18-24 hours. In case of gas formation the Durham tubes rise or/and  show bubbles. Turbidity of the medium accompanied by formation of gas within 48 hours is a positive presumptive test for the presence of E. coli and/or other coliform organisms. Prepared Broth becomes cloudy if stored at 2-8°C, but it should get cleared at room temperature. If there is fermentation in the tube incubated at 44°C after 8 to 24 hours, perform indole test by adding Kovac‘s reagent (TR 008). A positive indole test in a broth tube showing gas production at 44°C indicates the presence of Escherichia coli. If no fermentation occurs in the tube incubated at 37°C after 24 hours, the primary fermentation is assumed to be due to organisms other than coliforms.

 

Interpretation

Cultural characteristics observed after inoculating (103CFU/ml), on incubation at 35ºC for 18 - 24 hours.

 

Microorganisms

ATCC

Inoculum

(CFU/ml)

Growth

Gas production

 

 

Enterobacter aerogenes

13048

103

Good – Luxuriant

Positive

Escherichia coli

25922

103

Good – Luxuriant

Positive

Staphylococcus aureus

25923

103

Inhibited

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References

  1. Mallmann, W. L., and C. W. Darby. Uses of a lauryl sulphate tryptose broth for the detection of coliform organisms. Am J. Public Health. 31:12. (1941).
  2. Marshall, R. T. (ed.). Standard methods for the examination of dairy products, 16th ed., American Public Health Association, Washington, D.C. (1992).
  3. Vanderzant, C., and D. F. Splittstoesser (eds.). Compendium of methods for the microbiological examination of foods, 3rd ed. American Public Health Association, Washington, D.C. (1992).
  4. Eaton, A. D., L. S. Clesceri, and A. E. Greenberg (eds.). Standard methods for the examination of water and wastewater, 19th ed. American Public Health Association, Washington, D.C. (1995).
  5. U. S. Food and Drug Administration. Bacteriological analytical manual, 8th ed., AOAC International, Gaithersburg, MD. (1995).
  6. Cunnif, P. (ed.). Official Methods of Analysis AOAC International, 16th ed. AOAC International, Gaithersburg, MD. (1995).

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