Published: Sat, February 17, 2018
Medical | By Garry George

Genetic study of soil organisms reveals new family of antibiotics

Genetic study of soil organisms reveals new family of antibiotics

Global deaths from antibiotic-resistant infections are predicted to hit 10 million a year by 2050 unless new effective antibiotics are found.

Sean Brady, a chemical biologist at Rockefeller University in NY, and a team of colleagues, sequenced bacterial DNA they had taken from 2,000 soil samples collected across the United States. One way that they protect themselves is the production of harsh chemicals that kill off other bacteria.

They also knew that trying to culture all their soil samples in a lab would take forever, and that most would not replicate themselves under lab conditions anyway.

A newly discovered family of dirt-dwelling antibiotics could be our best weapon against treatment-resistant "superbugs".

Bob Hancock, a microbiologist at the University of British Colombia in Canada, says the method the team used to produce the antibiotics is "really blue-printable" and could be used to make a lot of new antimicrobial compounds. Malacidins work in a different way than most antibiotics: they use calcium to disrupt bacterial cell walls, a mechanism to which microorganisms don't seem to develop resistance.

Brady and his colleagues extracted over a thousand soil samples from USA soils, sequencing bacterial DNA and looking for potential antibiotics.

The antibiotics, called malacidins, are calcium-dependent, meaning they need calcium to be turned "on", according to the study. This then triggers bacterial cell destruction, killing the target bacterium. When they found what they were after, they cloned the genes, rearranged them and implanted them in a host organism, using fermentation to expand the sample. This process made it possible to test the unique properties of malacidin on MRSA-infected rats. 'This might be a way of reducing resistance'.

"So you have a molecule that will sterilize MDR [multidrug-resistant] Staph, with no resistance developed in the wound...and we don't see toxicity in the animal", Brady said.

The discovery came from a citizen science project - Drugs from dirt - started by Sean Brady of the Rockefeller University, US. In this new effort, the researchers studied microorganisms that live in soil as a possible source of new antibiotics-in order to survive, they, too, must have some means of fighting off bacterial infections. "I think this platform gives us some hope that we can go back to this tremendously powerful reservoir we used to look at in the past, and look at it in new ways and find new things", he said.

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