FAQs

If either of these happens, the sample can be further diluted until they get a specific
dilution where there is an observable count (within 1-300 colonies).

A. in case of high microbial load
Highly viscous samples should be appropriately diluted which is less viscous and will diffuse easily onto the fabric pad of CompactDryTM plate.
B. in case of low microbial load
Obtain 1.0 mL inoculum in 10 dilution, and inoculate small volume unto at least 5 different points in the CompactDryTM plate.

A. in case of high microbial load
Highly pigmented samples can also be diluted until the strong pigmentation fades.
B. in case of low microbial load
Sample can be diluted but inoculum volume must be adjusted as well. This can be done by filtering using a membrane filter to retain the needed sensitivity.

How long did you incubate ETB plate by counting?
It is known that certain Enterobacteriacae may grow quickly and alkalize the medium. As a result, Red/red-purple color colonies get discolored and form yellow colonies. It is easy, however, to count once at early (ex. 18hours).

Are there dark site (core) in center of diffused colonies ?
It is known that colonies of certain Enterobacteriacae may diffused. It is easy, however, to count dark point in center of each diffused colonies.

Dose your sample have extreme low or high pH?
Compact Dry ETB contains pH indicator dye. Because This medium is sensitive to extreme low or high pH, diluting or neutralizing samples is recommended.

CompactDryTM plate can be stored at refrigerated temperature. However, it should be tempered to room temperature before use.

The advised limit is 1-300 colonies, otherwise, adjust dilution.

Degree of pH can affect the recovery of pH sensitive microorganisms. To avoid that, naturalize the pH of the sample by dropping 1N NaOH or 1N HCl if the sample is too acidic or too basic, respectively.

These two CompactDryTM plates are both used for measuring the total microbial count but designed for different sample types. CompactDryTM TC is used for determining the microbial population in most solid, liquid, environmental, and air samples. On the other hand, CompactDryTM AQ is designed for heterotrophic microorganisms that require organic nutrient for growth, and these are universally present in water, food, soil, vegetation, air, among others.

The presence of Salmonella is detected by the combination of different test principles:
1) Alkalinisation of the medium by Salmonella’s lysine decarboxylase ability (medium colour will change blue purple to yellow).

2) Greening colony caused by decomposition of chromogenic substrate with specific enzyme of Salmonella (black colonies are generated by hydrogen sulphide producing Salmonella).

For the detection of lactic acid bacteria it is recommended to use Compact Dry TC. Samples should be diluted using sterilized saline and incubated under anaerobic conditions at 30 °C.

The medium contains the chromogenic enzyme substrate X-Phos which turns blue with most types of yeast.

Compact dry (XSA) medium is based on an improved mannitol-salt agar, during growth Staphylococcus aureus converts substrates for acid phosphatase and β-glucosidase into blue colored products. This results in formation of light blue colonies