R2A AGAR

Technical Data #1590a / 2013.08.18

R2A Agar is a solid medium used for the performance of plate counts. It is also suitable for analysis of drinking water by membrane filter procedures.

 


 

FORMULA
in grams per liter purified filtered water

Yeast Extract

0,5

Casein Peptone

0,25

Meat Peptone

0,25

Acid Hydrolysate of Casein

0,5

Dextrose

0,5

Starch

0,5

Dipotassium Phosphate

0,3

Magnesium Sulfate

0,024

Sodium Pyruvate

0,3

Agar

15,0

pH 7,2 +/- 0,2 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 2-8 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 18.1 g of dehydrated media in 1000 ml of purified filtered water. Heat with frequent agitation and boil for one minute. Sterelize at 121 C for 15 minutes. Mix thoroughly and dispense into sterile Petri dishes.


PROCEDURE
Prior to inoculate, the prepared media should be brought to room temperature.

  1. Directly, inoculate surfaces of the plate with membrane filter.
  2. Incubate at 35 C for 72 hours.


QUALITY CONTROL

Results after 48 hrs at 35C

Organisms

ATCC

Growth

Staphylococcus aureus

25923

+

Staphylococcus aureus

6538

+

Enterococcus faecalis

29212

+

Escherichia coli

25922

+

Bacillus subtilis

6633

+

Pseudomonas aeruginosa

9027

+


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


REFERENCES

  1. Reasoner, D.J., & E.E. Geldreich. 1985 A new medium for the enumeration and subculture of bacteria from potable water. Appl. Environ. Microbiol. 49:1
  2. Standards Methods for Examination of Water and Wastewater 1989 17th ed. APHA, Washington D.C.


CATALOGUE NUMBERS

Dehydrated media 500 grams QB-39-3728
Prepared media    
Plates, 100x15 mm 10/pkg 1590
Mono-plates, 100x15 mm 10/pkg 1590M
Plates, 50x9 mm 10/pkg 1591
Bottles, 200 ml 10/pkg 5217

 


 

 

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