Today I tried calibrating our pioreactors for higher ODs cultures since we expect our strain to grow up to OD 6. I calibrated with an initial max OD of 8.3 (to make sure there was some buffer area in case OD goes even higher than 6), 5 mL volume to add in each cycle, and minimum OD of 0.02. At the end of the calibration procedure I got the calibration curves, and could see that after OD of around 5 the curve falls (like in the image).
Is it then not possible to calibrate and use the pioreactors for higher OD cultures? or how is it recommended to do this?
Any possible input or feedback would be super helpful! Thanks!
There is certainly an upper saturation limit to our 90deg-based sensors, and ~5.0 OD600 sounds about right. In theory, itâs possible to infer beyond this saturation point (eg: some argument can be made that the cultureâs OD is âover the humpâ and can then determine cultureâs OD is > 5.0 OD600 by comparing it to the right hand side of the curve), but our software doesnât do this yet, and there arenât plans either (but let us know if you want this!).
If youâre performing a turbidostat, the solution is to set a lower target-OD than the saturation point.
If youâre doing batch cultures, you may need to manually sample at the end to get the final OD600, or do some post-analysis of the exported Pioreactor OD curves.
In theory, you can try increasing ir_led_intensity in the config to a value like 75 or 80. This may push back the saturation point.
