From the mud

New type of antibiotics found with the help of bacteria living in the soil

Natalia Pelezneva, Naked Science

Researchers from Rockefeller University in the USA announced the discovery of a new type of antibiotics called "malacidins" (malacidins). Scientists discovered these compounds by examining bacteria living in the soil. The first studies showed that malacidins are effective against methicillin—resistant Staphylococcus aureus, a microorganism that causes pneumonia and sepsis.

In the twentieth century, bacteria regularly became a source of new antibiotics, but in the last thirty years the industry has been experiencing a crisis — it is extremely rare to create new drugs. At the same time, medicine today is in particular need of such medicines due to the fact that pathogens become resistant to the usual antibiotics. According to the scientists who found malacidins, many types of soil bacteria have not been studied so far, so they can become a source of new effective drugs.

In search of new compounds, the researchers analyzed almost 2,000 soil samples, and volunteers collected these samples throughout the United States. Scientists were looking for certain motifs in the DNA of isolated bacteria — relatively short sequences of amino acids or nucleotides, presumably associated with certain functions. The researchers were interested in the motives characteristic of calcium-dependent antibiotics (drugs capable of destroying microorganisms only in the presence of calcium). These motives could turn out to be a "signal flag" indicating the existence of a longer genetic sequence associated with the ability to destroy microorganisms.

The found sequences were multiplied and, using genetic engineering methods, introduced into streptomyces bacteria, which are most often used for the synthesis of antibiotics. After a while, the bacteria began to produce malacidins. According to the researchers, the new drug interferes with the mechanism by which bacterial pathogens form cell walls. The drug was tested on rats infected with methicillin-resistant Staphylococcus aureus. The remedy proved to be effective, while the causative agent of the disease did not become resistant to the antibiotic over time.

Before becoming a component of medicines, malacidins must go through many stages of effectiveness and safety testing. At the same time, the used method of searching for new drugs can be applied today.

The study was published in the journal Nature Microbiology (Hover et al., Culture-independent discovery of the malacidins as calcium-dependent antibiotics with activity against multidrug-resistant Gram-positive pathogens).

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