CompactDry EC Ecoli Coliform – Shimadzu

CompactDry EC Ecoli Coliform – Shimadzu

Model: ETC
Code: 54056
Manufacturer: Shimadzu – Japan

Operating Procedure

1. Preparation of Compact Dry Plates

• Open the protective aluminum foil pouch.
• Remove one set of 4 plates (or the specific number required, e.g., 1–3 plates).
• Storage Note: Reseal the remaining plates immediately to protect them from light and moisture.
• Label each plate with the necessary identification information in the designated area.

2. Sample Preparation

• Preparation of Diluent (Butterfield's Phosphate Buffer):

  • Dissolve 34g of $KH_2PO_4$ in 500ml of distilled water.

  • Adjust the pH to 7.2 using $1N$ $NaOH$.

  • Sterilize via autoclave at 121°C for 15 minutes.

• Sample Dilution:

  • 1:10 Dilution: Aseptically weigh 50g of the sample and add 450ml of the prepared diluent. Homogenize using a stomacher for 2 minutes.

  • 1:100 Dilution: Transfer 1ml of the 1:10 dilution into 9ml of diluent and mix thoroughly.

3. Inoculation

• Using a sterile pipette, draw 1ml of the desired sample dilution.
• Lift the lid of the Compact Dry plate.
• Dispense the 1ml sample directly into the center of the plate surface. The sample will automatically diffuse across the medium.
• Replace the lid and proceed to incubation under the specified conditions.

Interpretation of Results

To ensure statistical accuracy, select plates containing between 10–150 colonies.

• Escherichia coli (E. coli): Count all blue or blue-purple colonies.
• Coliforms: Count all red or pink colonies.
• Total Coliforms: The sum of all colonies on the plate (red, pink, blue, and blue-purple).

Notes

• Overgrowth (TNTC): If the bacterial concentration exceeds 250 CFU per plate, the entire surface may turn a uniform red or pink color, making individual colonies indistinguishable. If this occurs, the sample must be further diluted and retested.
• Disposal: After the results have been recorded, all used plates must be sterilized via autoclaving (121°C for 30 minutes) before being discarded as biohazardous waste.