Noise in OD measurement, big spikes

Software
1

Hi,

I have been using the reactors for some time now and from time to time i see these really big spikes in the OD. I thought maybe it is the IR LED but that iutput looks normal, with values ranging from ca 0.05-0.2. When I try to export the Kalman filter and Raw OD, no files are downloaded.

In the experiment below it had been growing for a few days and i changed the exchange volume from 0.5 to 1mL just before the spikes started to appear, although i dont see how that can be connected.

It is very annoying with these spikes because they severely affect the alternative media fraction when using PID morbidostat.

pioreactor-noise
pioreactor-noise864×450 23.2 KB

2

Hi again!

I just want to let you know what I found. My shaking is at 900rpm and now I reduced the number of measurements to every 20 sec and stop shaking before OD measurement which has solved my problem.

I suspect that the reason these spikes come suddenly might be related to flocculation, meaning cells aggregate more and affect the light scatter. Pure speculation, but it might explain why it appears all of a sudden. I have sequenced a few samples from the pioreactors and in most samples I find mutations in the FLO genes.