> For the complete documentation index, see [llms.txt](https://help.sbtinstruments.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.sbtinstruments.com/mpd/workflows/track-growth-curve/measure-starter-culture.md).
# Measure starter culture
To track a full growth curve, you need a starter culture with a known concentration. From this, we calculate the volume required to reach a final concentration of 1 × 10⁷ cells/mL in the flask.
Here we have already prepared the overnight culture based on the guidance provided in [Optimize starter culture](/mpd/workflows/identify-optimal-inoculum-size.md).
{% stepper %}
{% step %}
**Retrieve a sample of the starter culture**
1. Use a serological pipette to aseptically transfer 10 mL of the overnight culture to a sterile vial.
2. Vortex thoroughly to disperse any cell clumps. For an *E. coli* culture it is usually sufficient to vortex 30 seconds at max speed.
{% hint style="warning" %}
## Proper vortexing is important for reliable results!
Ensure that you see a proper vortex forming. Poor vortexing can cause inadequate disaggregation, leading to low precision in replicates and non-linearity in dilution series.
Different pedestals exists for different sizes of vials. In the video, we show a multipurpose pedestal that works for many types of vials. Ensure that your pedestal is compatible with the given vial.
{% endhint %}
{% endstep %}
{% step %}
**Prepare the sample for BactoBox® measurement**
1. Prepare a 1:10 000 dilution using two sequential 1:100 dilution steps.
1. First make a 1:100 dilution:
1. Transfer 101 µL of your sample to 10 mL of diluent.
2. Vortex 10 seconds at maximum speed.
2. Then make the 1:10 000 dilution:
1. Transfer 101 µL of the 1:100 dilution to 10 mL diluent.
2. Vortex 10 seconds at maximum speed.
2. Transfer the tubing kit to the 1:10 000 vial.
{% endstep %}
{% step %}
**Measure the diluted sample on BactoBox®**
1. Transfer the tubing kit to the 1:10,000 vial.
2. Add metadata:
1. Dilution: 10 000
2. Label: Overnight\_culture
3. Click Measure to start a new measurement. Notice that there is a group icon on the button because you are within a measurement group.
4. After completing the measurement, Access will automatically calculate the bacterial concentration in the shake flask. To view the full table, drag the panel sideways.
{% endstep %}
{% step %}
**Clean the device**
1. Transfer the tubing kit to the disinfection vial.
2. Click Clean. The button in Access works the same way as the one on BactoBox®.
{% endstep %}
{% endstepper %}
## Summary
Now you know the bacterial concentration of your starter culture. Proceed to the next step to calculate the volume of starter culture needed to inoculate the growth curve flask.
---
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