Regarding the antimicrobial activity of plant extract which contains phenolic extract, firstly you do...
Disk diffusion method (Agar Cup - plate method ) which giving the antimicrobial potential of your phenolic extract by observing the zone of inhibition (potential of your drug to fight microbial organism).
For carrying this kind of activity you select any two gram positive, two gram negative and one fungal organism.
After observing the zone of inhibition, you carry the MIC (minimum inhibitory concentration) value of your phenolic extract for confirming the antimicrobial potential of your isolated phenolic extract from plant