Dear scientists;
I am going to purify a bacteriocin, the purification requires going through different stages. After each purification step I have to estimate the antibacterial activity (in arbitrary units (AU) per ml) and concentration of bacteriocins of the fractions obtained. Therefore, could you please help me how to estimate this activity (calculation method).
Cordially
You need a standardized test (maybe size of zone of inhibition or number of cells in a culture killed) and you can do a dilution series of your fractions to determine their activity in the test. For example, do a dilution series and spot 5 ul on a lawn and see the maximal dilution that gives your a zone of killing or inhibition. Then you can compare the dilution factors as your "activity" measurement.
Dear Michael thank you very much for your answer and your help
but still now I don't understand how to express this activity I mean 1AU/ml= ??
Best regards
An arbitrary unit means you get to decide yourself, it is arbitrary. You might want to do something like the dilution factor needed to abolish activity. So if at 100-fold dilution you have no activity but the next less dilute sample shows activity, then call it 100. But again you can just decide for yourself and define your term in the publication.
Dear Makhlouf Fatima Zohra,
You prepare serial dilutions and then perform an agar diffussion method seeding the same volume (if you perform a welld variant, you standardize the diameter of the well). The inverse of the last dilution that presents a halo inhibition corresponds to the AU in the seeded volume, then AU/ml is calculated. Here you will find a simple equation for this calculation.
https://doi.org/10.1016/j.foodcont.2014.12.037
Good luck
Dear @Mariana Emilia Cozzolino thank you very much for your guidance
Please could you send me a full text of this paper because I couldn't access it
Best regards
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