Elisabet Nuñez Gaitan
How to enumerate the microorganisms present in a sample?
- If the sample is solid, a first homogenisation step is required to prepare a 1/10 dilution.
- Once the sample is suspended or if the sample is liquid, serial dilute it with Dilucup®
- Plate 1 mL of the selected suspension(s) and incubate them.
- Count the colony-forming unit (CFUs). Remember that the plates should have between 30 and 300 CFUs to get a statistically valid result.
- Divide the average number of CFUs per the dilution level to get the number of microorganisms per mL or g in the original sample.
With Dilucup® Elegance don't worry about the volume of the diluent in the dilution process!
According to EN ISO 6887-1: 2017, the volume of the diluent cannot exceed a 2,0% deviation from 9,0mL. LabRobot still wants to be more accurate and that is why the volume in Dilucup® Elegance should never exceed 9,0ml ± 1,0%.
In 2020 none of the Dilucups manually controlled in our QC laboratory exceeded a ± 1% deviation from 9,0mL:
- 90,9% had a deviation of 9,0 mL ± 0,5%
- 0,3% between -0,5 and -1,0%
- 8,8% between +0,5 and +1,0%
Do you know any other serial dilution method with greater volume precision?
LabRobot was happy to participate in the Swedish movement “Håll Sverige Rent” (= Keep Sweden Tidy) and we dedicated a few minutes of our lunch break to collect plastic waste around our building.
If we all would do the same frequently, we would greatly reduce the amount of plastic materials in the nature and the oceans!