ISO 7932 (2004) method: Bacillus cereus

Process control Food and animal feeding stuffs

Horizontal method for the enumeration of presumptive Bacillus cereus - Colony-count technique at 30°C

  • 1 Quantitative process control with CRM-BC

    • Pink colonies with precipitation halo. The characteristic reaction of on MYP
    Characteristic reaction: Pink colonies with precipitation halo.

    Best Practice

    The single strain CRM-BC contains Bacillus cereus spores which are not heat-resistant. This material can only be used for vegetative cell analyse

    1. Use a quantitative reference material (CRM-BC) with a known number of Bacillus cereus.
    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 (MYP) by spread 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 (24 ± 3) h to (44 ± 4) h.
    6. Count the colony forming units and register in a control chart.
    7. The characteristic reaction is: Pink colonies with precipitation halo.

    Kind of reference material Biosisto product for this control method Control Strain NCCB number
    Single-strain reference material
    CRM-BC
    		 Bacillus cereus 100292
    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-BC veg

    • Pink colonies with precipitation halo. The characteristic reaction of on MYP
    Characteristic reaction: Pink colonies with precipitation halo.

    Best Practice

    The single strain RM-BCveg contains Bacillus cereus vegetative cells and heat-resistant spores. This material can be used for vegetative cell analyse and the spore analyse

    1. Use a quantitative reference material (RM-BC veg) with a known number of Bacillus cereus.
    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 (MYP) by spread 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 (24 ± 3) h to (44 ± 4) h.
    6. Count the colony forming units and register in a control chart.
    7. The characteristic reaction is: Pink colonies with precipitation halo.

    Kind of reference material Biosisto product for this control method Control Strain NCCB number
    Single-strain reference material
    RM-BC veg
    		 Bacillus cereus 100292
    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-BLES

    • Pink colonies with precipitation halo. The characteristic reaction of on MYP
    Characteristic reaction: Pink colonies with precipitation halo.

    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 (MYP) by spread 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 (24 ± 3) h to (44 ± 4) h.
    6. Count the colony forming units and register in a control chart.
    7. The characteristic reaction is: Pink colonies with precipitation halo.

    Kind of reference material Biosisto product for this control method Control Strain WDCM number NCCB number
    Multi-strain reference material
    RM-BLES
    		 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.

  • 4 Quantitative process control with RM-BCE.00001MH

    • Best Practice

    The single strain RM-BCE.00001MH contains Bacillus cereus vegetative cells and heat-resistant spores. This material can be used for vegetative cell analyse and the spore analyse

    1. Use a quantitative reference material (RM-BCE.00001MH) with a known number of Bacillus cereus.
    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 (MYP) by spread 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: Pink colonies with precipitation halo.

    Kind of reference material Biosisto product for this control method Control Strain CCUG number
    Single-strain reference material
    RM-BCE.00001MH
    		 Bacillus cereus 10781
    The Biosisto reference material in this table is used in the best practice for Quantitative process control according ISO 17025.