In September 1928, bacteriologist Dr. Alexander Fleming returned from his summer vacation and arrived at his London lab at St. Mary’s Hospital.
Fleming had been studying common staphylococcal bacteria, culprits behind diseases as pneumonia. Examining his bacterial colonies, Fleming found that an uncovered Petri dish near the window had been contaminated with the common mold Penicillium notatum.
When he examined this dish under the microscope, he was surprised. The mold appeared to be inhibiting bacterial growth! The rest is history. Penicillin, derived from the mold, became a revolutionary medicine, curing infections that would have otherwise been fatal.
Penicillin was also the precursor to modern antibiotics, which led to the decline of many diseases. And now, scientists have revived Fleming’s original strain of Penicillin and sequenced its genome. Let’s take a look at their research, and what implications their results may have for the future of microbiology.
Fleming's Mold - It’s Alive!
A research team, led by Professor Timothy Barraclough from the Department of Life Sciences at Imperial College, London and the Department of Zoology at Oxford, “originally set out to use Alexander Fleming’s fungus for some different experiments”, until they realized no one had ever sequenced penicillium’s genome before.
The researchers set to work, reviving the historic, 92-year-old mold from a frozen sample at CABI’s (Centre for Agriculture and Bioscience International) culture collection. After extracting DNA from the revived mold, the researchers zeroed in on its genome, focusing on two specific types of genes: those that generate enzymes that produce penicillin, and those that regulate the production of those enzymes.
The researchers compared Fleming’s mold with two modern U.S. strains of the fungus that are used to produce antibiotics, and discovered intriguing differences in their enzyme-regulating genes. While both strains of penicillium had the same basic genetic code, modern U.S. strains had more copies of regulating genes, meaning they were capable of producing more penicillin. Enzymes produced by both strains also varied slightly.
Why did this genetic difference occur? The researchers think that it arose from the molds’ “arms race” with microbes. More specifically, as microbes racked up resistance, molds fine-tuned their penicillin production in response to their changing environment. Thus, the difference between the two strains suggests that each evolved according to the varying factors in their environments.
Implications for the Future
Ayush Pathak, the study’s first author, said that the team’s research “could help inspire novel solutions to combating antibiotic resistance”.
Currently, penicillin used in mainstream antibiotics such as Augmentin is refined from Penicillium molds that are genetically modified for greater production, As bacteria develop drug-resistance and mutate into lethal superbugs, the study results could shed light into how antibiotic production can be improved.
Let's take a look at this old black-and-white video celebrating the discovery of penicillin!
Sources: Nature, CNN, LiveScience, PBS, Britannica, SciTechdaily