Antibiotics: A world beyond moldy fruit

Blog entry

Streptomycin, ampicillin, kanamycin, neomycin, gentimicin, et al…Antibiotics. There are a ton of them out there, and it all started with Alexander Fleming’s seminal discovery that his bacterial cultures wouldn’t grow around the mold that was contaminating his dishes (Thank goodness he kept a slovenly lab, eh?). Actually, what he saw was that this mold was destroying the bacteria surrounding it. After some investigation, he discovered that the mold, a member of the Penicillium genus secretes a substance he originally referred to as “mould juice” and was toxic to Staphylococcus.He named the substance “penicillin” and just like that, modern medicine was revolutionized. A little bit later (decades actually), the lab was revolutionized as well, with the appearance of molecular biology techniques and selection agents. Anecdotally, this is the same mold that you see growing on your oranges and lemons.  Crazy.

Whether you use them to protect your precious cells from bacteria, or other cells (the ones that didn’t take up your construct, for example), antibiotics are super useful and help make all our lives livable. Literally.  This week I’ll talk about antibiotics as means to prevent prokaryotic contamination and next week I’ll tackle the topic of using them as selection agents for cell transfection.

We’ve all been there: You open the incubator and there it is all cloudy and yellow, mocking your aseptic technique.  Bacteria.   Hey. It happens, and it would happen much more often if we didn’t have a little trick up our collective sleeves. Most labs use antibiotics prophylactically and they use either a mix of penicillin/streptomycin or something else such as gentamicin.  Pen-strep, as we all call it, is a popular choice simply because it casts a wide net.  Penicillin is highly effective against gram-positive bacteria while streptomycin is effective against gram-negative AND those gram-positive bacteria that may be resistant to penicillin. Gentamicin, a chemical relative of streptomycin, was actually found to be superior to pen-strep as it can wipe out a broad spectrum of bacteria.

Check it out. I was 2 years old when this was published:

Which begs the question: Why don’t more people use it?  Personally I think it may be a bit too strong, having some undesirable effects on the eukaryotic cells in the culture. So, it may be wise to strike that balance of good, proper aseptic technique and an “OK” antibiotic mix…..AAAAAAAND guess who sells a boatload of antibiotics. Gemini! Just give them a call. They are super nice and forever and would be thrilled to tell you what Gemini offers.  See you next week!


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