Effects of Different Growth Mediums on Strength of Penicillin Produced

Friday, 13 February 2015
Exhibit Hall (San Jose Convention Center)
Marisa Shotwell, Arlington, VA
Discovered in 1928 penicillin was the first wonder drug but since its initial discovery usage has declined due to the increase of antibiotic resistant bacteria. But still to this day all pharmaceutical grade penicillin is based off of a strain found in the 1940s on a rotten cantaloupe. The growing antibiotic resistance is one of the biggest problems facing the medical industry but they high cost to research new drugs makes it unpopular. Since many drugs are based off of the original strain of penicillin the purpose of this experiment was to test the effect of different growth mediums, cantaloupe, honeydew melon, and avocado, on the strength of penicillin said growth produce as determined by testing against Staphylococcus epidermidis and comparison to 10 ul of pharmaceutical grade penicillin. The three mediums were chosen due to the results of a previous experiment, but this experiment was done to focus and get more definitive results with less chance of error, changes to the procedure were also made from the first experiment to this one. The penicillium mold was grown on the raw growth mediums for 10 days before the mold was moved to a chemical based media in which the penicillin was secreted. Next diffusion disks saturated in the media containing the penicillin were put on plates containing Staphylococcus epidermidis. The area of inhibition was then calculated by weighing an outline, drawn on plastic sheeting, of the area of inhibition. It was discovered that on average cantaloupe had the highest area of inhibition followed by avocado and honeydew melon.  The pharmaceutical grade penicillin was supposed to act as a reference but because the amount of penicillin secreted in the media was not measured it wasn't able to be used in that way but was instead used to compare the areas of inhibition when making observations. Since Cantaloupe had the highest area of inhibition this experiment supported previous research.