We're making an E. coli intracellular expression product. In one batch of fermentation, OD was reduced by half within one hour, and phage contamination was found by post-electron microscopy. Subsequently, the entire fermentation system and workshop were treated, such as autoclave, formaldehyde fumigation, and ozone disinfection. Subsequent fermentation showed no contamination. But bacteriophage contamination was found again this week. Would like to ask how to do follow-up prevention? We found that the two fermentation contamination were both cultured at 30 degrees, while the intermediate culture at 37 degrees did not show contamination. Are there any temperature-sensitive phages?
Weifeng Zheng There are many bacteriophages with optimal propagation temperature around 30oC. In your case it can be a multihost phage with main host living at lower temperatures comparing to E. coli.
I think it more likely the issue is not the difference in temperature but rather moving from the intermediate culture to the large scale. Are you going from a flask to a fermentor? It may be something in the fermentor pipeline is permitting the phage contamination.
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