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An antibiotic made from human bacteria

Scientists at the University of San Francisco have purified an antibiotic substance made by a common bacterial species found in the human body, and have named it Lactocillin.

December 2014

Scientists at the University of San Francisco have purified an antibiotic substance made by a common bacterial species found in the human body, and have named it Lactocillin. IMA LAB

 

Bacteria that normally live inside us or on our skin have genetic blueprints which enable them to produce thousands of molecules that actually act like drugs, and some of these molecules may well be suitable to serve as the basis for new human therapeutics, according to UC San Francisco researchers.

In a study published in the September 11 issue of Cell, the scientists describe how they purified and solved the structure of one of the molecules they had identified, an antibiotic which they named Lactocillin: this is made by a common bacterial species, Lactobacillus gasseri, found in the microbial community within the vagina.
Roughly one third of all medicines used in clinical practice are developed either from microbes or plants, and for many years countless teams of biologists have been investigating and analyzing organisms from all over the world and from every kind of environment in the hope of finding new pharmacologically active substances.

Yet only recently have scientists started turning their attention to the human microbiome — the trillions of microorganisms that live in or on our bodies ­— as a possible source of potential medicines.
This immense population includes both beneficial and harmful microbes, ranging from bacteria to viruses, fungi and others, which coexist inside the human body, in the intestines, on the skin, in the respiratory tracts, in the mouth and in the vagina.

Currently, the Human Microbiome Project run by the US National Institutes of Health is carrying out a census of the population of the microbiome and is creating an ever-expanding database of the genomes of hundreds of species of microorganisms.

Using an algorithm called ClusterFinder, the researchers have identified 3,118 distinct bacterial gene clusters (BGCs) from various parts of the human body. These BGCs, the researchers say, represent the DNA blueprint for the production of microbial natural products, and provide a template for future experimental efforts to discover small biologically active molecules from the microbiome. These molecules represent a promising starting point for studying microbe–host interactions at the level of molecular mechanisms and represent a potentially rich source of therapeutics.

“We used to think that drugs were developed by drug companies, approved by the FDA, and then prescribed by physicians, but we now think there are many drugs of equal potency and specificity being produced by the human microbiota,” said Dr. Fischbach, one of the members of the University of California San Francisco team.
“We demonstrate that Lactocillin has potent antibacterial activity against a range of Gram-positive vaginal pathogens, and we show that Lactocillin and other thiopeptide BGCs are expressed in vivo by analyzing human metatranscriptomic sequencing data,” wrote the investigators.

However, at the moment ­— the new study reveals ­­— the genus-level analysis commonly used to identify bacteria within human microbiomes is not detailed enough to predict which drug-like molecules the bacteria make.

“We need to learn what these molecules are and what they are doing,” Fischbach said.
“This could represent a pool of molecules with many tantalizing candidates for drug therapy.

 

References:

http://www.ucsf.edu/news/2014/09/116921/our-microbes-are-rich-source-drugs-ucsf-researchers-discover

http://www.cell.com/Cell/abstract/S0092-8674%2814%2901102-7