Amphotericin: Use and Applications
I never really had a reason to use the phrase ”The Fungus Among us.” Until Now. That’s because I’m going to share my thoughts on amphotericin (Yes, I have thoughts on amphotericin!). Most of us know this fungicide by one trade name or another (insert yours here) and I’m willing to bet that if you’ve been doing cell culture for any extended time, you’ve either used it or talked about it. That’s because there is, indeed, fungus among us. Everywhere … and in some places, it is much more prevalent than others.But no matter where you are, fungus will find its way into your cell cultures. It’s only a matter of time, dear scientist … A MATTER OF TIME.
So what do you do when you look into the scope and see the dreaded beasties taking over? You get your amphotericin! There are currently 2 types of amphotericin: A and B. The stuff you may have in your freezer should be Amphotericin B. It’s the one with the defined anti-fungal properties. Biochemically, it’s a polyene. From what I can remember from organic chemistry, that means it has a bunch of alternating single and double bonds on the carbon chain (okay, biochemists, bring on the emails!). Amphotericin B’s mechanism of action is such that it interacts with ergosterol, a molecule found only in fungal cell membranes . This interaction makes the fungal cells leaky and they spill out essential molecules, killing the fungal cells.
Now, theoretically, this biochemical interaction makes Amphotericin B perfectly safe for your cells, as ergosterol is not found in plant or animal cells. However, personal experience tells me to give you this bit of advice: Use it carefully, and only for as long as you truly need it. Some picky cells like ES cells and their derivatives, tend to lose some gusto after prolonged exposure to Amphotericin B (say, 2 weeks straight) and sometimes won’t recover even after you remove it.
But, if you’re like me and your lab was in a swamp, extra measures to ensure clean cultures are necessary. Some folks use a “get-it-all” solution of penicillin, streptomycin, and Amphotericin B (most of us know it as “anti-anti”) and put it right in their medium for constant protection from those tiny undesirables. This is generally a decent idea and doesn’t get me all bent out of shape because the Amphotericin B is at a pretty low dose and is designed to nip any potential issue in the bud. That said, this anti-anti mix may not be the way to go if you can actually SEE the contamination, due to the lower levels of the stuff found in it. In that case you would want to pipette Amphotericin B directly into your cultures after several PBS rinses to get as much stuff out of your cultures as possible. Gemini has some info on their website about using anti-anti vs. straight amphotericin B depending on your needs. Also, don’t forget, you can always call on this blogger-type-guy if you have any questions or issues!
Good day and may you only find yeast in your homebrews!