Bacteria that normally live in and upon us have genetic blueprints that enable them to make thousands of molecules that act like drugs, and some of these molecules might serve as the basis for new human therapeutics, according to UC San Francisco researchers who report their new discoveries in the September 11, 2014 issue of Cell. The scientists purified and solved the structure of one of the molecules they identified, an antibiotic they named lactocillin, which is made by a common bacterial species, Lactobacillus gasseri, found in the microbial community within the vagina. The antibiotic is closely related to others already being tested clinically by pharmaceutical companies. Lactocillin kills several vaginal bacterial pathogens, but spares species known to harmlessly dwell in the vagina.

This example suggests that there may be an important role for many naturally occurring drugs -- made by our own microbes -- in maintaining human health, said the senior author of the study, Michael Fischbach, PhD, an assistant professor of bioengineering with the UCSF School of Pharmacy, who has established a career discovering interesting molecules made by microbes.

"We used to think that drugs were developed by drug companies, approved by the FDA, and prescribed by physicians, but we now think there are many drugs of equal potency and specificity being produced by the human microbiota," Fischbach said.

About a third of all medicines used in the clinic are derived from microbes and plants, Fischbach said. These include antibiotics like penicillin, numerous drugs used in cancer chemotherapy, and cholesterol-lowering drugs. Although those who prospect for drugs from microbes have been combing the depths of the oceans and probing exotic soils around the globe, only now have scientists begun to look within our own bodies.

There are hundreds of bacterial species associated with each of us, and thousands of distinct strains among them. We do not all harbor the same species, and different species are found at different body sites.