New research, funded in part by the U.S. National Center for Complementary and Alternative Medicine (NCCAM), suggests that some of the bacteria that share the human body manufacture antibiotics and that these substances may be capable of fighting infection.
The researchers, from the University of California, San Francisco; the
University of California, Santa Cruz; Indiana University; Washington
University School of Medicine; and Harvard Medical School, published
their findings in a recent issue of the journal Cell.
The human
microbiome – the name given to the trillions of microorganisms that live
in and on the human body – consists of beneficial and harmful microbes
that include bacteria, viruses, fungi and others. In this study, the
researchers purified and solved the structure of a thiopeptide
antibiotic (lactocillin) produced by Lactobacillus bacteria that make up
part of the vaginal microbial community. Thiopeptides are a relatively
new class of antibiotics that have previously been found in organisms
that inhabit the soil and the seas.
The researchers also
determined that lactocillin had an activity profile similar to that of
other thiopeptides (which are active against Gram-positive, but not
Gram-negative, bacteria), with activity against Staphylococcus aureus,
Enterococcus faecalis, and Corynebacterium aurimucosum, all of which can
cause illness, but not against Escherichia coli. Lactocillin was
inactive against other Lactobacillus species – suggesting that over time
these bacteria had become resistant to the compound.
Using an
algorithm called ClusterFinder, the researchers identified 3,118
distinct bacterial gene clusters (BGCs) from various parts of the human
body. These BGCs, the researchers said, represent the DNA blueprint for
production of microbial natural products, and provide a template for
future experimental efforts to discover biologically active small
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.
Learning how BGCs in the human microbiome function
holds great promise for understanding microbe–host and microbe–microbe
interactions, the researchers concluded.
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