We inherited an old incubator and it showed mould growth in the water tray, so we used an internal service for formalin fumigation (and formalin deactivation with ammonia). They did everything to the book and fumigated the incubator. We proceeded to wipe the residue from the incubator and to run it, cleaning the water tray. There was a smell afterwards, that fainted and then disappeared, and I tested the incubator with cells in a flask that did not seem to be affected anymore. We proceeded to use the incubator, but later (about 1.5 months) realized that cells growing in plates showed increased cell death in that incubator compared to control cells in a control incubator - no contamination present, just cell death. We believe the filter caps protect cells in flasks from being affected. Does anyone have experience with this issue and know what to do to get rid of it? Our current approach is to wipe it again thoroughly.
Follow up: After a second thorough wipe, cell growing in plates survived in the incubator but grew more slowly than in the non-fumigated incubator. Before we could do the third rinse, the incubator grew mould again at the bottom, indicating that spores may have survived the formalin fumigation somewhere within the inaccessible areas of the incubator. We have now discarded the use of this old incubator for tissue culture.
Was there a HEPA filter in the incubator & was it replaced? Maybe residual formalin is still there.
Other than that, another thorough wipe down with 70% Ethanol in double distilled water is what I’d do. Good luck!
Thanks Susan! No HEPA filter, it's quite old. There was a vacuum filter fitted between the CO2 cylinder and the incubator, but has been replaced. Finger crossed this second wipe does it. Cheers!
Check the pH of the media used or make new media. Maintain humidity in the incubator using 0.2 gm copper sulphate in 100ml dist. Water and make 1L solution of it.
All the best
Happy Research
Julia Gala de Pablo
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