I work in an enzymology lab focusing towards protein crystallography. We express our gene in pET-28(a) expression vector inside E.coli BL-21(DE3) host leading to protein expression. The problems are-
1. Recently we are observing a filamentous type of cell growth in LB broth inside the flasks(images attached).
2. Presence of these filaments are visible to naked eye after the flask is kept at 37C for 2-3 hours.
3. It is clearly not due to excess cell growth because this type of cell growth is very unusual and a recent event in our lab.
4. The moving particles look like finely shredded filament of cotton and are gathering at the bottom of flask pretty soon in the absence of shaking.
5. We are also getting a smear kind of cell accumulation inside centrifugation bottles (centrifuge machine is perfectly working and bottles are fine).
** We have a Bacteriophage facility next door. Is there any possibility to get the contamination from there? (Because some of them look like an accumulation of dead cells).
*** Our lab also performs study of bacteriophage from waste water though the facility is in different floor. Could if be possible that the contamination comes from the garments of scholars visiting our lab from that facility?
If this is happening after induction it's probably your over expressed protein causing lysis, and the stuff you're seeing is gunk from the cells being busted open. I would suspect that before bacteriophage infection, though that is possible.
I can't see the MOV file though because I don't have the codec for it though.
I concur with Alexandra Johnson that this is lysis debris, however it looks to me that it most likely is bacteriophage infection. As you mention you have a phage lab next door. Usually with expression induced toxicity you get growth stopping but not normally lysis such as what you see in the picture. But it does depend upon the protein.
This could easily be a phage infection. Does this happen with BL21 without the plasmid? Grow them on LB without antibiotics and see.
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