EC BROTH WITH DURHAM TUBES

Technical Data #2914a / 2010.08.31

EC Broth medium with Durham tubes is used for the determination and enumeration of coliforms organisms in water.

 

FORMULA
in grams per litre purified filtered water

Tryptose..................................20.00 g

Sodium Chloride.......................5.00 g

Lactose.....................................5.00 g

Dipotassium Phosphate............4.00 g

Bile salts no 3...........................1.90 g

Monopotassium Phosphate.......1.50 g

pH 6.9 ± 0.2 at 25 ̊ C

This approximate formula may be adjusted and/or enriched to obtain best results.

PRECAUTIONS
This medium is for laboratory use only.

STORAGE
Store prepared media at 2-30° C protected from direct light and dehydrated powder, in a dry place, in tightly-sealed containers at 2-25° C.

SIGN OF DETERIORATION
Media should not be used if the expiry date has passed. Prepared media should not be used if there are signs of contamination or deterioration (shrinking, cracking, evaporation or discoloration). Do not use dehydrated media if it is caked.

DIRECTIONS

Suspend 37.4 grams of the medium in 1000 mL of distilled purified water. Heat with frequent agitation until the medium is completely dissolved. Dispense in tubes with Durham gas collecting vials for gas detection and boil for 5 minutes. Sterilize at 121ºC for 15 minutes. DO NOT OVERHEAT.

PROCEDURE

Inoculate sample into tubes and incubate at 37̊° C for 24 hours. Lactose fermentation with gas production is evidence of the presence of coliforms.

QUALITY CONTROL

Results after incubation at a temperature of 44.5ºC ± 2ºC and observed after 24 ± 2 hours.

Microorganisms             ATCC          Growth      Gas Production

Bacilus subtilis                6633          inhibited              -

Enterobacter aerogenes    13048        inhibited               -

Escherichia coli                25922         good                 +

Streptococcus faecalis       19433        inhibited              -

LIMITATIONS OF METHOD
This medium is only a part of the identification. Other tests may be required.

REFERENCE

Hajna and Perry 1944 A.P.H.A. Ray B. 1986 Impact of bacterial injury and repair in food microbiology. Its past, present and future J. Food Prot.

CATALOGUE NUMBERS

Deshydrated medium            500 g                QB-39-1506

Prepared medium

Durham tubes                           10pqt                2914