I have been using Antifoam B for E.coli fermentation. I have used this without a problem in the past. I use a 5% solution that is pumped into the fermenter on a need basis as detected by the fermenter foam probe.
Recently my cultures started dying/stopped growing when the antifoam solution is pumped in the culture. I believe this a bad batch, has anyone had a problem like this before? I was hoping to just get a discussion going on what type of antifoam you use and how you use it.
i.e. what is the stock concentration, are you pumping it in, or adding manually, or adding a certain amount before the culture is started?
Thanks
Instruments: Sartorius Biostat Aplus Fermenter
Chemicals: Antifoam B (Sigma). I dilute to 5% and use that for the antifoam detection probe/pump.
We typically use Antifoam C. For the stock, we autoclave a 10% solution and add at MAX 1 or 2 ml per liter. This is more than enough for our reactor (very rich media, easily bubbly, Clostridial growth). Maybe your adding too much and the culture has reached a point of toxicity. I would suggest adding the same conc you use to a growing flask and seeing if it also halts growth. If so, reduce it 10-fold and see if the same happens. If so, it may be phage as noted above.
Hope this helps.
Thank you guys for your answers. I considered a phage contamination, but it only happens as soon as I add the antifoam. That would mean it's in the antifoam stock solution? More likely source for the phage contamination?
Robert: You add the antifoam as part of the formulation of the medium or do you drip in 1 to 2 ml per liter over the course of the fermentation.
How long are your runs?
My runs are 5 - 10 days.
Here is how I've done it before. I would have a 100 mL bottle of 5% antifoam solution and the fermenter would drip in as much as needed over the course of the fermentation.
I ordered a new bottle and am making new stocks. Not sure where the contamination is coming from.
You have been using Antifoam B for E.coli fermentation. You have used this without a problem in the past. You use a 5% solution that is pumped into the fermenter on a need basis as detected by the fermenter foam probe. So, there were no problem with E. coli phage contamination, and the antifoam stock solution.
However, recently your cultures started dying/stopped growing when the antifoam solution is pumped in the culture. You believe this a bad batch. This matter may because: (1). when you ordered a new bottle and you were making new stocks, the new bottle weren't sterilized yet, as a result , the new stocks were contaminated, (2) The Sartorius Biostat Aplus Fermenter used must be fully sterilized both the body and the cover of the fermentor in order to avoid contamination which cause your cultures started dying/stopped growing when the antifoam solution is pumped in the culture
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