Finding Antibiotic Producing Bacteria From Soil

The purpose of this experiment is to find as many possible candidates for bacterial producing antibiotics. This can be tested through many methods; this specific experiment consisted of analyzing soil. There are so many existing antibiotics that the immune system is building up a resistance to, it has become necessary to find new ones to fight against bacterial infections in humans. Since the present antibiotics we are seeing are beginning to lose their effectiveness and the best way to find bacteria is in healthy soil, this experiment shows how to cultivate pure candidates for antibiotics. Utilizing a sample of soil I extracted from my backyard, I diluted the soil with the goal of seeing if any zones of inhibition were present. After identifying the possible candidates, I created a Master Plate with the purpose of narrowing down my findings in search of more pure candidates. I then tested the colonies to see if they had a resistance to antibiotics with the technique of screening. This is the process of testing colonies against gram-positive and gram-negative pathogens to see if any zones of inhibition result. Metabolic studies and sequencing were also performed to identify the organism. Plates 1 (10^1) and 2 (10^2) showed 1-10 zones of inhibition. The other plates proved to have no existence of zones of inhibition. Taking from plates 1 and 2, I made my Master Plates. Originally both Master Plates failed because the bacteria over-grew, so I restarted the process narrowing it down to 4 colonies on each plate. Master Plate 2 failed and Plate 1 was a success. With the most pure candidates determined, I tested all of them against gram-negative (Escherichia coli and Pseudomonas putida) and gram-positive (Stephylococcus epidermidis, and Enterococus faecalis) bacteria to see if the colonies had an antibiotic resistance. My candidates resulted in being gram-positive, indicating they were antibiotic-producing.