So many of us are aware that penicillin comes from mold, but the mold isnt pure penicillin. You cant ball it up and eat copious amounts to cure bacterial infections.
How they get this blue-green fuzz and extract just the medicine from it? How do scientists know what theyre extracting in general?
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The original penicillin was excreted from the mold. Now days penicillin is manufactured in laboratory from chemicals not taken from mold anymore.
The key is that at low pH, penicillin isn’t very soluble in water, and is slightly more soluble in certain organic solvents, like amyl acetate. at neutral pH it’s more soluble in water than in those other solvents.
* grow a bunch of penicillium mold in a big fermenting vat (a bioreactor). filter out all the solids (the mold and any other particles and sludge) and keep the liquid, which is mostly water, and contains the penicillin
* add acid to reduce the pH of the mixture to about 2. Penicillin isn’t very soluble at low pH.
* add a bunch of amyl acetate and mix it up. Then let it sit for a while and the butyl acetate will separate from the water and float on top.
* At low pH The penicillin is more soluble in the amyl acetate than it is in water, so this top layer will contain most of the penicillin. keep this, and get rid of the water.
* filter the amyl acetate through a charcoal filter to remove all the other impurities.
* now add some water, with phosphate buffer at a neutral pH of 7. at neutral pH the penicillin will be more soluble in the water. let it settle, and most of the penicillin will be in the water layer.
* repeat these steps a few more times. add acid, extract with amyl acetate, then extract with pH-7 phosphate buffer.
* when it’s as pure as you can get it, you want to turn it into a potassium salt. so add a bunch of potassium acetate and you’ll end up with crystals of penicillin potassium salt.
And boom! you’ve got penicillin!
Bonus fact: Amyl acetate smells like bananas!
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