[Nikako]

Hello to both of you,

I am facing a similar issue of variability in the OD values but at higher ODs as well (OD=0.4 using the turbidostat functionality of the bioreactor, which results in an OD of ~0.2 [more precisely OD is contained between 0.16 and 0.19] when culture’s OD is measured in a cuvette and at 600nm wavelength). I am not sure if the variability comes from the cells growing and then getting diluted when OD gets above 0.4, but in some cases, I could see a notable difference depending on the orientation of the culture tube. I also observe variability in OD with fresh medium, but if left untouched, the OD values are quite stable. The issue is that I am taking samples out of the culture tube when my bacterial population reaches OD=0.4, which leads to some displacements, I assume. Could you let me know the amount of variability you observed in OD values at ODs around 0.4 (or 0.2) if you have the numbers?

To clarify, the culture tube’s surface is cleaned with isopropanol before placing it in the ChiBio module.

@Neythen, were you able to solve your issue? And if yes, how did you manage?

@Harrison, regarding the plastic diffuser, would it be possible to get some of these plastic pieces? I checked and the spectrometers of my ChiBio reactors don’t have them. I was planning to go with 2mm thick opaque acrylic sheets otherwise. Also, I am not sure to understand how the light diffuser can improve the OD readings as it would be located after the glass surface of the culture tube.

Thank you in advance for your reply.

Niko

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