04/04/2008
Bacteria Can Eat as Well as Produce Antibiotics
The Science
Antibiotics are a crucial line of defense against bacterial infections. Nevertheless, several antibiotics are natural products of microorganisms that have as yet poorly appreciated ecological roles in the wider environment. Researchers isolated hundreds of soil bacteria with the capacity to grow on antibiotics as a sole carbon source. Of 18 antibiotics tested, representing eight major classes of natural and synthetic origin, 13 to 17 supported the growth of clonal bacteria from each of 11 diverse soils. Bacteria subsisting on antibiotics are surprisingly phylogenetically diverse, and many are closely related to human pathogens. Furthermore, each antibiotic-consuming isolate was resistant to multiple antibiotics at clinically relevant concentrations. This phenomenon suggests that this unappreciated reservoir of antibiotic-resistance determinants can contribute to the increasing levels of multiple antibiotic resistance in pathogenic bacteria.
Summary
Unexpected new microbial defensive capabilities are emerging from genomic analyses of microbial diversity from the Genomics:GTL program and genome sequencing projects at the DOE Joint Genome Institute. Professor George Church and colleagues at the Harvard Medical School Systems Biology Center report on yet another remarkable example of microbial adaptability in the April 4 issue of the journal Science. It has long been recognized that bacteria living in soils fight to maintain their territory by producing antibiotics against their competitors; such antibiotics (such as streptomycin) have been widely used in medicine to fight infection. In the course of surveying soil microbes for useful capabilities in environmental remediation or bioenergy production, the researchers discovered a further adaptation “some microbes can eat their enemies” ammunition. This means that the original defensive purpose of these microbial antibiotics can be used as a dietary source when other nutrients are lacking. This new result may have implications for the general evolution of antibiotic resistance of microbes in a variety of health and environmental settings.
Principal Investigator
George M. Church
Harvard Medical School
References
Dantas, G. M. O. A. Sommer, R. D. Oluswasegun, and G. M. Church. 2008. “Bacteria Subsisting on Antibiotics,” Science 320,100–103. DOI:10.1126/science.1155157.