It's the same sort of soil bacteria that ivermectin was developed from

"Geosmin (1), whose name means “earth odor”, is a volatile microbial metabolite that is responsible for the characteristic smell of moist soil . In the soil, geosmin production is attributed to a single genus of bacteria, called Streptomyces"

also the smell of beetroots

Studies show that beets taste like dirt to some people because they contain a chemical called GEOSMIN (which means “dirt smell”), an organic compound produced by a type of actinobacteria called Streptomyces.