OXIDATIVE-FERMENTATIVE MEDIUM

Technical Data #2057a / 2013.08.31

OF Medium is a semisolid medium, supplemented with carbohydrate, for determination of the oxidative-fermentative metabolism of this carbohydrate by gram negative bacilli. Motility and gas-production may be determinated due to the semisolid nature of the medium. Tubes should be inoculated in duplicate: cover one with 1-2 ml of sterile mineral oil for the fermentative metabolism.

 


 

FORMULA
in grams per liter purified filtered water

Casein Peptone

2,0

Sodium Chloride

5,0

Potassium Phosphate, dibasic

0,3

Bromthymol Blue

0,03

Agar

2,5

pH 7.0 +/- 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 9,8 g of dehydrated media in 900 ml of purified filtered water. Heat with frequent agitation and boil for one minute. To prepare OF 1% Dextrose, add 100 ml of 10% Dextrose solution. To prepare OF Control, add 100 ml of purified filtered water. Sterilize at 118 C for 15 minutes. Cool to 45-50 C. Mix gently and dispense into sterile culture tubes.


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

  1. From a pure overnight culture on TSI, prepare a bacterial heavy suspension.
  2. Inoculate 2 tubes with a straight needle not far than 1/2 cm from the bottom of the tubes.
  3. Add 1-2 ml of sterile mineral oil to one of the 2 tubes. Loosen cap of the other tube
  4. Incubate at 35 C for 24-48 hours. Discard only after 4 days of incubation.


QUALITY CONTROL

Results after 24 hrs at 35C

Organisms

ATCC

Reaction

 

 

 

OF CONTROL

 

 

Pseudomonas aeruginosa 27853 O - F -
Klebsiella pneumoniae 13883 O - F -
     
OF 1% DEXTROSE    
Pseudomonas aeruginosa 27853 O + F -
Klebsiella pneumoniae 13883 O + F +
Alcaligenes faecalis 19018 O - F -


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


REFERENCES

  1. Hugh, R., E. Leifson 1953 The taxonomic significance of fermentative versus oxidative metabolism of carbohydrates by various gram-negative bacteria. J. Bacteriol. 66:24-26
  2. Lennette, E.H., Ballows, A., Hausler, W.J.Jr., and Shadomy, H.J. Manual of Clinical Microbiology. 4th ed. 1985 Washington D.C.: American society for Microbiology.
  3. Mac Faddin, Jean F., Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria Vol.1 1985 Baltimore, MD. Williams & Wilkins.
  4. Washington, J.A. 1981 Laboratory Procedures in Clinical Microbiology Springer-Verlag, New York


CATALOGUE NUMBERS

Dehydrated media 500 g QB-39-3411
Dextrose, granulated 500 g QB-39-1210
     
Prepared media    
Tubes, 16x125 mm    

OF Control

10/pkg 2057

OF 1% Dextrose

10/pkg 2617
  100/box 2617-H

 


 

 

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