Hi there!
We are trying to understand the implied growth rate values generated in our turbidostat runs.
We always notice that the implied growth rate rises at the beginning of our fermentation and then reaches a peak just before the target OD. When the system starts to dilute the culture to maintain it at a steady state at the target OD, the implied growth rate always drops, often reaching close to 0 or at times negative values.
I guess this means that the growth rate is obtained using the change in OD over time rather than via calculating the dilution rate of the turbidostat?
Is there then a way to check whether our cells keep growing at the same rate as during the initial phase to reach our target OD (taking into account the dilution events)?
Thanks in advance!
Belen
Hi @belenadiego,
I guess this means that the growth rate is obtained using the change in OD over time
Yes, this is how it’s calculated.
When the growth-rate is near 0 during dilutions, do you see the OD still increasing at all?
Do you mind sharing some charts screenshots of the growth-rate and OD readings?
Hi Cameron,
The OD increases between dosing events (orange line). Every time the target OD (0.3) is reached again, the system dilutes the culture by adding 1 mL of medium and removing 1 mL of medium. That’s how we keep the OD at a target of 0.3. We have a dosing event every 24 min approx. This can be seen in the orange line with the multiple sudden decreases once the OD reaches 0.3.
All this makes that once the target OD is achieved, the implied growth rate (in red) goes to 0 or even negative values.
Hm, yea I don’t really like that - it doesn’t look like part of our algorithm is working in this instance. Can you send me the exports of the “OD readings”, and export for “Dosing event log” to cam@pioreactor.com
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