CRITERION™ LAURYL TRYPTOSE BROTH

Cat. no. C5980 CRITERION™ Lauryl Tryptose Broth 71.2gm
Cat. no. C5981 CRITERION™ Lauryl Tryptose Broth 500gm
Cat. no. C5982 CRITERION™ Lauryl Tryptose Broth 2kg
Cat. no. C5983 CRITERION™ Lauryl Tryptose Broth 10kg
Cat. no. C5984 CRITERION™ Lauryl Tryptose Broth 50kg

INTENDED USE

Hardy Diagnostics CRITERION™ Lauryl Tryptose Broth is used for detecting coliform organisms in water, wastewater, and foods.

This dehydrated culture medium is a raw material intended to be used in the making of prepared media products, which will require further processing, additional ingredients, or supplements.

SUMMARY

Lauryl Tryptose Broth is prepared according to the formulation of Mallmann and Darby.(5) Sodium lauryl sulfate, by inhibiting most gram-positive microorganisms, serves as a selective agent for coliforms. The addition of lactose to the medium allows for detection of rapid lactose-fermentation by coliforms. Essential growth ingredients are provided by casein peptone which is composed of nitrogen, carbon compounds, sulfur and trace ingredients. Potassium phosphate acts as a buffer while sodium chloride serves to maintain osmotic equilibrium. A durham tube is present in order to detect the production of gas.

Coliforms grown in Lauryl Tryptose Broth ferment lactose and produce gas. Other bacteria are either inhibited or grow without producing gas.

FORMULA

Gram weight per liter: 35.6gm/L
Tryptose 20.0gm
Lactose 5.0gm
Sodium Chloride 5.0gm
Monopotassium Phosphate 2.75gm
Dipotassium Phosphate 2.75gm
Sodium Lauryl Sulfate 0.1gm

Final pH 6.8 +/- 0.2 at 25ºC.

* Adjusted and/or supplemented as required to meet performance criteria.

STORAGE AND SHELF LIFE

Store the sealed bottle(s) containing dehydrated culture medium at 2-30ºC. Dehydrated culture medium is very hygroscopic. Keep lid tightly sealed. Protect dehydrated culture media from moisture and light. The dehydrated culture media should be discarded if it is not free-flowing or if the color has changed from its original light beige.

Store the prepared media at 2-30ºC.

PRECAUTIONS

METHOD OF PREPARATION FOR DEHYDRATED CULTURE MEDIA

1. Suspend 35.6gm of the dehydrated culture media in 1 liter of distilled or deionized water.

2. Warm slightly to dissolve completely.

3. Dispense into tubes containing inverted fermentation vials.

4. Autoclave at 121ºC. for 15 minutes.

PROCEDURE AND INTERPRETATION OF RESULTS

For information on procedures and interpretation of results, consult listed references or refer to the prepared media Instructions for Use (IFU) for Cat. No. K33.

LIMITATIONS

Turbidity without gas production is not indicative of a positive test.

A precipitate or cloudiness may form in refrigerated broth. Media will become clear when warmed to room temperature.

Prior to inoculation of the medium, it may be necessary to invert the tube in order to release any bubbles that may be trapped in the durham tube. Bubbles that are not removed before inoculation may lead to false-positive results.

Since the nutritional requirements of organisms vary, some strains may be encountered that fail to grow or grow poorly on this medium.

MATERIALS REQUIRED BUT NOT PROVIDED

Standard microbiological supplies and equipment such as autoclaves, incinerators, and incubators, etc., are not provided.

QUALITY CONTROL

Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Escherichia coli
ATCC ® 25922
A 24hr 35°C Aerobic Growth; gas bubble in durham tube
Enterococcus aerogenes
ATCC ® 13048
A 24hr 35°C Aerobic Growth; weak gas bubble in durham tube at 48 hours
Salmonella enterica
ATCC ® 14028
A 48hr 35°C Aerobic Growth; no gas production
Serratia marcescens
ATCC ® 8100
A 48hr 35°C Aerobic Growth; no gas production
Staphylococcus aureus
ATCC ® 25923
B 48hr 35°C Aerobic Partial to complete inhibition; no gas production

User Quality Control

PHYSICAL APPEARANCE

CRITERION™ Lauryl Tryptose Broth powder should appear homogeneous, free-flowing, and light beige in color. The prepared media should appear clear, and amber in color.

REFERENCES

1. MacFaddin, J.F. 1985. Media for Isolation, Cultivation, Identification, Maintenance of Bacteria, Vol. I. Williams & Wilkins, Baltimore, MD.

2. The United States Pharmacopeia. U.S. Pharmacopeial Convention Inc., Rockville, MD.

3. Speck. Compendium of Methods for the Microbiological Examination of Foods. APHA, Washington, D.C.

4. Greenberg, et al. Standard Methods for the Examination of Water and Wastewater. APHA, Washington, D.C.

5. Mallmann, W.L. and C.W. Darby. 1941. Am. J. Publ. Health; 31:127.

6. Williams, ed. Official Methods of Analysis of the Association of Official Analytical Chemists. AOAC, Arlington, VA.

7. FDA. Bacteriological Analytical Manual. AOAC, Gaithersburg, MD.

8. Greenberg, et al. Standard Methods for the Examination of Water and Wastewater. APHA, Washington, D.C.


053116gr