Bacterial Diversity is Why Penicillin Doesn't Kill "Good" Bacteria

Bacteria are everywhere! They can be found in chains or clusters, have different shapes, thrive in different environments, and some can be harmful or could be necessary to maintain our health. Some are even used to produce antibiotics to treat infection. While there is so much research that has be done to observe bacteria, there are still so many new discoveries. One of the greatest discoveries in the medicine was Alexander Fleming finding a weird mold that prevented the growth of Staphylococcus on a cantaloupe!

Gram-negative (left) vs gram-positive (right) bacteria

The mold is called Penicillium rubens which is now used to produce an antibiotic to treat many infections caused by gram-positive and gram-negative bacteria. This discovery became crucial in preventing death from infection towards the end of World War II. Although Fleming’s discovery in 1929 was very important, it didn’t become relevant around the time of World War II. Fleming observed and noted the effects of the mold on bacteria but was unable to isolate the antibacterial substance alone. The Oxford research group, which included many biochemists, was determined to purify penicillin, and show that it can prevent disease from different types of deadly bacteria.

Morphological and molecular characterization of isolated Penicillium rubens

This advance in medicine showed that there are bacteria, fungi, and other organisms that can be used to kill pathogenic bacteria, but not necessarily harm any of the “good” bacteria. This specific characteristic of bacteria is what allowed the world of antibiotics grow. If you have ever taken an antibiotic and experienced any side effects including stomach pain, UTIs, vomiting or diarrhea, it is because the antibiotics have now killed the “good” bacteria that your body actually needs to perform every functions.

Once human studies began with penicillin, it became clear that there was going to be a high demand. Penicillin from the cantaloupe serves as the “parent” strain that is used to drive the production of commercial strains as penicillin needed to be mass produced. Although penicillin was a huge advancement in medicine, it started with understanding bacterial diversity. As stated before, penicillin is only useful against certain bacteria, not all. There are new antibacterial agents that have been discovered to target different bacterial morphologies. There are also new bacteria being discovered that have different characteristics that are still being understood. At the end of the day, understanding bacteria and its diverse world is going to be important to continue with antibiotics as resistance is on the rise!