Part of Thermo Fisher Scientific
MAXIMUM RECOVERY DILUENT (PEPTONE SALINE DILUENT)
Code: CM0733
a protective and isotonic diluent for maximal recovery of micro-organisms (ISO/DIS 6649)
Typical Formula* | gm/litre |
Peptone | 1.0 |
Sodium chloride | 8.5 |
pH 7.0 ± 0.2 @ 25°C |
Directions
Dissolve 9.5g in 1 litre of distilled water. Dispense into the final containers and sterilise by autoclaving at 121°C for 15 minutes.
Description
Maximum Recovery Diluent combines the protective effect of peptone in the diluting solution with the osmotic support of physiological saline1,2. The low concentration of peptone does not cause multiplication of the organisms within 45 minutes (@ 20-25°C) of dilution of the sample. The isotonic strength of the diluent ensures recovery of organisms from various sources which may be vulnerable in distilled water or aqueous suspensions.
Technique
Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared medium at room temperature.
Appearance
Dehydrated medium: Straw coloured, free-flowing powder
Prepared medium: Colourless, clear solution
Quality control
The diluent is inoculated with each organism, separately, and held at 20 -25°C. Counts of colony forming units are obtained at 0 minutes and 45 minutes from inoculation, using suitable nutrient medium. The results are compared, using the time "0" count as the base bench mark.
Positive controls: | Expected results |
Escherichia coli ATCC® 25922* | ±50% original count |
Escherichia coli ATCC® 8739* | ±50% original count |
Staphylococcus aureus ATCC® 25923 | ±50% original count |
References
1. Straker R. P. and Stokes J. L. (1957) Appl. Microbiol. 5. 21-25.
2. Patterson J. W. and Cassells J. A. (1963) J. Appl. Bact. 26. 493-497.
3. ISO/DIS 6649. Meat and Meat Products-Detection and Enumeration of Clostridium perfringens.