I recently performed a lab to test different concentrations (20-99%) of isopropyl alcohol and its inhibition of E. coli growth. My control was an antibacterial disk, and what I did was I dabbed the disk in each concentration and put it on the agar with the E. coli. I dabbed it enough so it wasn't soaking wet but it still had some liquid.
Unfortunately, I had no results at all from the alcohol-soaked disked, but I know the experiment should work because the antibacterial disks for all Petri dishes worked.
I don't know why the alcohol did not work at all though, especially since it is proven to be effective as a disinfectant at least for E. coli.
If anyone has a link with this exact lab being tested, or something similar (isopropyl alcohol and effect on zone of inhibition in bacteria labs) that would be amazing. Concentrations 20,30,40,50,60,70,80,99% -Disk diffusion, I put the bacteria by streaking across the quadrants -I dipped the disks until it was soaked then dabbed enough to make sure it wasn't dripping -Negative control:sterile disk In the middle, positive control: antibacterial disk on quadrant A -I was going to measure zone of inhibition but there was none produced for all 12 plates except for quadrant A containing the antibacterial disk.