does fungi swim or move? - cell culture contamination (Mar/18/2005 )

hi, everyone, would you please tell me whether fungi is able to swim in media? i suspect that my cells are contaminated by fungi, which is visible under 200X microscope magnification. . i don't think it's bacteria contamination, because i add some contaminated media to Amp-LB/agar plate but there is nothing. by the way, i used strep/pen antibiotics in my media. is fungi larger than bacteria?
thanks a lot.

---

Should not you add some contaminated media to LB/agar plate without Amp instead of with?

---

probably bacteria if its swimming, but you can't test for bacterial contamination with selective agar because the ampicillin will kill what you are trying to detect.

Jon

---

thanks all your reply. i have a few stupid questions :

if ampicillin is able to kill or inhibit the growth of the contaminant, could i use ampicillin in my cell culture media? is ampicillin different from penicillin?

---

Ampicillin and penicillin are slighty different in what types of bacteria take them up if memory serves (and resistance is modified by a side chain on ampicillin), but they hit cell wall synthesis more or less the same way. I'm pretty sure ampicillin will kill bacteria just as well (if not better) than straight penicillin, but I think ampicillin is more expensive than penicillin though. For a quick "rescue my cells!" cleaning it's worth a shot though, it shouldn't hurt the cells anyway. One thing to keep in mind is pen-strep breaks down over time when media is heated; this keeps it from hanging around in the culture, but if you're warming media in advance and take too long you're removing all the antibiotic from it. Something to keep in mind; it might be your stuff is contaminated because the media has no antibiotic left in it. And finally, if it's a new source of cells you ordered they may have sent you a contaminated batch, in which case you turn around and politely scream at them to correct their mistake .

---

Should we always add streptomycin and penicillin together in the same medium? I thought it is enough with one type. What do you do?

Thanks.

---

HI,
My experience with fungi has been as either yeast (floating, large, grape-like) or mold (floating, clearly macroscopic, very spore-spiderwebby-like). They are slow growing and clear up with a fungicide.

Regarding pen/strep...I imagine there are many strains of bacteria that are resistant (hence why we get bacterial contamination in our plates sometimes...or maybe a higher dose is needed), but I've sometimes gone to the extreme of using Cipro to clear up contamination in a plate I just couldn't throw away.

Good luck
Junie

---

if you think you have contamination by fungi, use fungizone.

---

We usually add a mix of the two; I gathered that was pretty standard, since they work by different mechanisms so you were less likely to get resistant strains to both. Dunno how just adding one will work, though the antibody is there more as a backup than something you absolutely rely on to protect your cells (most of THAT depends on your sterile technique really; in my experience almost inevitably bacterial contamination was either in the sample to begin with or was added accidently by the person doing the culture). If it's fungal contamination, you probably want to scrub out your incubator with ethanol as completely as possible to ensure you don't have spores in there that'll reinfect other cultures.

---