Horizontal method for the enumeration of Coliforms - Colony-count technique
ISO 4832 (2006) method: Coliforms
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1 Quantitative process control with RM-CFREU
- Use a quantitative reference material (RM-CFREU) with a known number of Citrobacter freundii.
- Defrost the material at room temperature for 30 minutes.
- Mix well before use and dilute the material so countable numbers are inoculated on the media (VRBL) by pour plate method.
- 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.
- Incubate at (30 ± 1) °C for (24 ± 2) h.
- Count the colony forming units and register in a control chart.
- The characteristic reaction is: Purplish-red colonies with or without precipitation halo.
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2 Quantitative process control with RM-EC
- Use a quantitative reference material (RM-EC) with a known number of Escherichia coli serotype O6:H1.
- Defrost the material at room temperature for 30 minutes.
- Mix well before use and dilute the material so countable numbers are inoculated on the media (VRBL) by pour plate method.
- 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.
- Incubate at (30 ± 1) °C for (24 ± 2) h.
- Count the colony forming units and register in a control chart.
- The characteristic reaction is: Purplish-red colonies with or without precipitation halo.
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3 Quantitative process control with RM-ECO.00012MM
- Use a quantitative reference material (RM-ECO.00012MM) with a known number of Escherichia coli.
- Defrost the material at room temperature for 30 minutes.
- Mix well before use and dilute the material so countable numbers are inoculated on the media (VRBL) by pour plate method.
- 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.
- Incubate at (30 ± 1) °C for (24 ± 2) h.
- Count the colony forming units and register in a control chart.
- The characteristic reaction is: Purplish-red colonies with or without precipitation halo.
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4 Quantitative process control with RM-ECO.00012BH
- Use a quantitative reference material (RM-ECO.00012BH) with a known number of Escherichia coli.
- Defrost the material at room temperature for 30 minutes.
- Mix well before use and dilute the material so countable numbers are inoculated on the media (VRBL) by pour plate method.
- 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.
- Incubate at (30 ± 1) °C for (30 ± 1) °C.
- Count the colony forming units and register in a control chart.
- The characteristic reaction is: Purplish-red colonies with or without precipitation halo.
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5 Quantitative process control with RM-ECO.00013BL
- Use a quantitative reference material (RM-ECO.00013BL) with a known number of Escherichia coli serotype O6:H1.
- Defrost the material at room temperature for 30 minutes.
- Mix well before use and dilute the material so countable numbers are inoculated on the media (VRBL) by pour plate method.
- 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.
- Incubate at (30 ± 1) °C for (24 ± 2) h.
- Count the colony forming units and register in a control chart.
- The characteristic reaction is: Purplish-red colonies with or without precipitation halo.
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6 Quantitative process control with RM-BLES
- Use a quantitative reference material (RM-BLES) with a known number of Microorganisms.
- Defrost the material at room temperature for 30 minutes.
- Mix well before use and dilute the material so countable numbers are inoculated on the media (VRBL) by pour plate method.
- 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.
- Incubate at (30 ± 1) °C for (24 ± 2) h.
- Count the colony forming units and register in a control chart.
- The characteristic reaction is: Purplish-red colonies with or without precipitation halo.

Best Practice
The single strain RM-CFREU is used for the enumeration of Enterobacteriaceae

Best Practice
The single strain RM-EC is used for the enumeration of coliforms
Kind of reference material | Biosisto product for this control method | Control Strain | WDCM number | ||
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Single-strain reference material | Escherichia coli serotype O6:H1 | 00013 | |||
The Biosisto reference material in this table is used in the best practice for Quantitative process control according ISO 17025. |

Best Practice
The single strain RM-ECO.00012MM is used for the detection and enumeration of coliforms

Best Practice
The single strain RM-ECO.00012BH is used for the enumeration of Coliformen

Best Practice
The single strain RM-ECO.00013BL is used for the enumeration of Coliformen
Kind of reference material | Biosisto product for this control method | Control Strain | WDCM number | ||
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Single-strain reference material | Escherichia coli serotype O6:H1 | 00013 | |||
The Biosisto reference material in this table is used in the best practice for Quantitative process control according ISO 17025. |

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.
Kind of reference material | Biosisto product for this control method | Control Strain | WDCM number | NCCB number | |
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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. |