A backyard soil sample yields a lasso-shaped antibiotic with a new target

The find

The bacterium, a species of Paenibacillus, came from soil collected in a garden in Hamilton, Canada. The team grew it slowly for weeks, a method that coaxes out microbes that usual quick cultures miss, and screened for anything that killed other bacteria.

The active molecule turned out to be a lasso peptide: a short chain that ties itself into a knot, with its tail threaded through a ring. That shape makes lasso peptides very resistant to heat and to enzymes that chew up ordinary peptides.

What it does

Lariocidin stops bacteria making proteins by binding the small subunit of the ribosome, at a site not used by any antibiotic in clinical use. Bacteria resistant to existing drugs were still sensitive, and in the lab the bacteria were slow to develop resistance to it.

It did not harm human cells in tests, and it reduced infection in mice infected with Acinetobacter baumannii, a hospital germ high on the World Health Organization’s list of priority pathogens.

What comes next

The natural molecule is not potent enough or made in large enough amounts to be a drug yet. The group is working on versions that are stronger and easier to produce. New antibiotic classes are rare; the last ones that reached patients against hard-to-treat bacteria took a decade or more from discovery.

Source Jangra M. et al., Nature, March 2025

Amino Weekly reports research. It is not medical advice and never gives doses.