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Bacteria becoming resistant to the antibiotics we currently use is a serious concern for medical professionals and researchers. To combat this resistance, researchers are searching for new antibiotics in all sorts of unusual places!
The first true medical antibiotic (from the ancient Greek “anti” meaning opposing, and “bio” meaning life) was penicillin, which was discovered by Alexander Fleming in 1928. Prior to its discovery, there were no effective treatments for illnesses such as pneumonia and strep throat. Fleming discovered penicillin by accident. He was growing bacteria in special containers called petri dishes, and he noticed on one of the plates there was mold growing on part of the plate, and there were no bacteria growing around it. This mold was Penicillium notatum, and Fleming could tell there was something about this mold that was stopping the bacteria from growing. Following its discovery, researchers worked out how to grow this mold on a large scale, extract the bacteria-killing molecule, and purify it for medical use as the antibiotic called penicillin.
For most of us the word ‘antibiotic’ conjures up images of a tablet, but in fact an antibiotic is the name given to a molecule (produced by a microorganism like a fungus or bacteria) that is capable of either killing other microorganisms or preventing them from growing. In the case of the Penicillium notatum mold, a fungus, it produces a molecule that prevents some bacteria from making cell walls. Without a cell wall, the bacteria die. Other antibiotic compounds work in other ways too, such as preventing bacteria from dividing, or stopping the bacteria from making plasma membranes.
Roughly 90% of the antibiotic medicines currently in use come from “good” bacteria and fungi that help us fight infection instead of causing it. Unfortunately, as more and more “bad” bacteria that do cause infection evolve to be resistant to these existing antibiotics, scientists are looking far and wide for new “good” microorganisms that might help in the fight against microorganisms that make us sick. These researchers are searching in all sorts of extreme environments, such as deep-sea vents, caves, jungle, hot springs, and deserts. Traditionally, the microorganisms they discover in these environments are then painstakingly grown and tested in the laboratory one at a time to see if they could help, but genomics is helping to speed this process up.
Because researchers have identified the genes in known microorganisms that encode antibiotic molecules already in use in medicine, they can look at the genes of new microorganisms and see if they have any similar looking genes. And they don’t even need to look at one microorganism at a time: they can use “metagenomics” to look at the genetic information present in an environmental sample, such as a soil sample, which may contain of hundreds of thousands of different microorganisms, to look at all of their genomes at once. This is enabling researchers to identify genetic sequences that encode promising molecules much more quickly, although there is still a high level of rigorous testing that is required before these new molecules can be used in humans. This means that it takes a long time before these newly discovered molecules can be approved and used in medicine.
In addition to searching for promising genes in “good” microorganisms, researchers can also look at the genomes of “bad” microorganisms that have developed antibiotic resistance to determine which genes have enabled them to become resistant to current antibiotics. The researchers may then be able to work out new ways that antibiotics can better defeat these dangerous microorganisms.
It is also worth noting that in addition to “good” microorganisms, there are lots of other places that researchers can look for antibiotic molecules. In recent years, researchers have also been investigating lots of different organisms; plants with known medicinal properties, animals like sea sponges and bullfrogs, and algae. This search for beneficial molecules in nature is called “bioprospecting”. It is hoped that combining these three approaches will lead to the discovery of a variety of new and effective antibiotics that are fatal to harmful bacteria, but do not harm human cells.
We have come a long way since that accidental discovery by Fleming in 1928, and the field of genomics is primed to make a positive impact on the field of antibiotic discovery. Who knows which far flung corner of the earth the next big discovery will come from, but it is bound to have an impact on how we treat illness in the future!
If you would like to read about a project we are funding that is researching drug resistance you can click here.
You may also like to read about how in 2021 researchers from the U.K. and Australia determines a new mechanism that could help researchers find new antibiotics in soil bacteria.