> 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/encyclopedia/identify-harvest-time-old-steps/track-hourly.md).

# Track hourly

Continue hourly measurements throughout the deceleration and stationary phases until the cell concentration stabilizes. We will detail what *stable* means on next page.

The sample workup is identical to the step by step guide provided in [Track deceleration phase](/mpd/encyclopedia/identify-harvest-time-old-steps/track-deceleration-phase.md).

<figure><img src="https://142487182-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FseAjVXi9YrPNSfdp1OXS%2Fuploads%2F3K0zqcF480QTk5Kk9Elf%2FOptiseeding_-7_workup_1%3B10000.avif?alt=media&#x26;token=f8ffaef4-1831-4dc0-b5fe-699684685794" alt=""><figcaption></figcaption></figure>

## Step by step

{% stepper %}
{% step %}

### Retrieve a sample

Use a serological pipette to sample 1 mL culture. Transfer to a 5 mL centrifuge tube. Note down the sampling time.
{% endstep %}

{% step %}

### **Disaggregate cell clumps**

Vortex the vial 1 minute at maximum speed to disaggregate[^1] cell clumps. See [Break up clumps and chains](/advanced/advanced-sample-preparation/break-up-clumps-and-chains.md) if your bacterium needs more aggressive disaggregation[^1] than this.
{% endstep %}

{% step %}

### Arrest further cell divisions

Transfer to a cold rack to stop cell growth. Let the sample cool for at least 1 minute.
{% endstep %}

{% step %}

### **Dilute 1:100**

Transfer 101 µL of your sample to 10 mL of diluent. Vortex 10 seconds at maximum speed.
{% endstep %}

{% step %}

### **Dilute 1:10 000**

Transfer 101 µL of the diluted sample to 10 mL of diluent. Vortex 10 seconds at maximum speed.
{% endstep %}

{% step %}

### **Measure the diluted sample on BactoBox®**

Transfer the tubing kit to the 1:10 000 vial.

Add the metadata:

* Dilution: <kbd>10 000</kbd>
* Label: <kbd>staph-epi-harvest</kbd> or similar.

Then press <kbd><mark style="background-color:purple;">Measure<mark style="background-color:purple;"></kbd> in Access to start a new measurement.

After completing the measurement, Access will automatically calculate the cell concentration in the culture in the field <kbd>Cells/mL × Dil</kbd>.
{% endstep %}

{% step %}

### Measure repeat #2 and #3

Repeat steps 4–6 two times more to obtain triplicate repeats. Vortex the sample briefly prior to transferring 101 µL.

Use exactly the same input information as in step 5. When identical sampling time and label is used, Access will treat the data as replicates.
{% endstep %}

{% step %}

### Conclude measurements

Stop the measurements when the relative change is <5% two consecutive measurements. We will detail the calculations in [Conclude engineering run](/mpd/encyclopedia/identify-harvest-time-old-steps/conclude-engineering-run.md).
{% endstep %}
{% endstepper %}

## Summary

You tracked the cultures hourly throughout deceleration and stationary phase with triplicate repeats. In the next step, [Conclude engineering run](/mpd/encyclopedia/identify-harvest-time-old-steps/conclude-engineering-run.md), you will decide when to conclude the experiment.

[^1]: Break up clumps or chains of cells


---

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