ISO 4833-1 (2013) method: Colony Count

Process control Food chain

Horizontal method for the enumeration of microorganisms - Part 1: Colony count at 30°C by the pour plate technique

  • 1 Quantitative process control with CRM-SA

  • Growth. The characteristic reaction of  on MPCA
    Characteristic reaction: Growth.

    Best Practice

    The single strain CRM-SA is used for the enumeration of Coagulasepositive staphylococci. In accordance with ISO 4833-1, PCA can also be used instead of MPCA.

    1. Use a quantitative reference material (CRM-SA) with a known number of Staphylococcus aureus.
    2. Defrost the material at room temperature for 30 minutes.
    3. Mix well before use and dilute the material so countable numbers are inoculated on the media (MPCA) by pour plate method.
    4. Best results are obtained when a practicable range of 80 cfu to 120 cfu per plate with a minimum number of 50 cfu per plate is used.
    5. Incubate at (30 ± 1) °C for (72 ± 3) h.
    6. Count the colony forming units and register in a control chart.
    7. The characteristic reaction is: Growth.

    Kind of reference material Biosisto product for this control method Control Strain WDCM number
    Single-strain reference material Staphylococcus aureus 00034
    The Biosisto reference material in this table is used in the best practice for Quantitative process control according ISO 17025.
  • 2 Quantitative process control with RM-BLES

  • Growth. The characteristic reaction of  on MPCA
    Characteristic reaction: Growth.

    Best Practice

    The multi-strain RM-BLES contains, Bacillus cereus, Lactobacillus plantarum, Escherichia coli WDCM 00013 and Staphylococcus aureus WDCM 00034 in milk. This material can be used for several specific standards. The influence of interfering bacteria is also performed. It is easy to use by making one serie of dilution.

    1. Use a quantitative reference material (RM-BLES) with a known number of Microorganisms.
    2. Defrost the material at room temperature for 30 minutes.
    3. Mix well before use and dilute the material so countable numbers are inoculated on the media (MPCA) by pour plate method.
    4. Best results are obtained when a practicable range of 80 cfu to 120 cfu per plate with a minimum number of 50 cfu per plate is used.
    5. Incubate at (30 ± 1) °C for (72 ± 3) h.
    6. Count the colony forming units and register in a control chart.
    7. The characteristic reaction is: Growth.

    Kind of reference material Biosisto product for this control method Control Strain WDCM number NCCB number
    Multi-strain reference material Bacillus cereus 100292
    Lactobacillus plantarum 100293
    Escherichia coli serotype O6:H1 00013 100297
    Staphylococcus aureus 00034 100294
    The Biosisto reference material in this table is used in the best practice for Quantitative process control according ISO 17025.
  • 3 Quantitative process control with RM-BSUBT

  • Growth. The characteristic reaction of  on MPCA
    Characteristic reaction: Growth.

    Best Practice

    The single strain RM-BSUBT containing vegetative cells and heat-resistant spores in milk. This material can be used for analyses cell and spore of Bacillus subtilis as well for Colony count analyses.

    1. Use a quantitative reference material (RM-BSUBT) with a known number of Bacillus subtilis subsp. spizizenii.
    2. Defrost the material at room temperature for 30 minutes.
    3. Mix well before use and dilute the material so countable numbers are inoculated on the media (MPCA) by pour plate method.
    4. Best results are obtained when a practicable range of 80 cfu to 120 cfu per plate with a minimum number of 50 cfu per plate is used.
    5. Incubate at (30 ± 1) °C for (72 ± 3) h.
    6. Count the colony forming units and register in a control chart.
    7. The characteristic reaction is: Growth.

    Kind of reference material Biosisto product for this control method Control Strain WDCM number
    Single-strain reference material Bacillus subtilis subsp. spizizenii 00003
    The Biosisto reference material in this table is used in the best practice for Quantitative process control according ISO 17025.
  • 4 Quantitative process control with RM-CC

  • Growth. The characteristic reaction of  on MPCA
    Characteristic reaction: Growth.

    Best Practice

    The multi strain RM-CC that contains, Staphylococcus aureus WDCM 00034, Bacillus subtilis WDCM 00003 and Escherichia coli WDCM 00012 in broth. This material can be used when the proces must be controlled with interfering bacteria or if you want to use this material for multi purposes.

    1. Use a quantitative reference material (RM-CC) with a known number of Microorganisms.
    2. Defrost the material at room temperature for 30 minutes.
    3. Mix well before use and dilute the material so countable numbers are inoculated on the media (MPCA) by pour plate method.
    4. Best results are obtained when a practicable range of 80 cfu to 120 cfu per plate with a minimum number of 50 cfu per plate is used.
    5. Incubate at (30 ± 1) °C for (30 ± 1) °C.
    6. Count the colony forming units and register in a control chart.
    7. The characteristic reaction is: Growth.

    Kind of reference material Biosisto product for this control method Control Strain WDCM number NCCB number
    Multi-strain reference material Echerichia coli 00012 72002
    Staphylococcus aureus 00034 100294
    Bacillus subtilis 00003 89157
    The Biosisto reference material in this table is used in the best practice for Quantitative process control according ISO 17025.