Like many other organisms, bacteria have to compete for resources and have developed a wide array of strategies to use in that fight. Because microbes often generate antibacterial compounds, they present a potential source of antibiotics that humans can use. Soil microbes have already helped us create some of our best medicines. Now researchers have found another interesting source of antimicrobial compounds - bacteria that are associated with insects. Led by Cameron Currie, a University of Wisconsin-Madison professor of bacteriology, scientists found that some insect-associated microbes help shield their hosts from infection.
After searching microorganisms taken from 1,400 insects from all over North and South America, the team showed that microbes linked to insects were better than soil microbes at stopping pathogens. The findings have been reported in Nature Communications.
A new antibiotic was identified in this study. The researchers named it cyphomycin after finding it with a Brazilian ant that farms fungus. Cyphomycin successfully combated fungal infections in a mouse model and did not cause side effects. The team has already submitted a patent for the compound.
This research is the biggest effort yet to assess the antibiotic activity of insect-associated microbes."We could collect 400 insects in a few days," said Currie. The insects that were gathered provided the researchers with over 10,000 microbes. They also collected an additional 7,000 microbial strains from plants and soil.
One bacterium, Streptomyces, came on the scene about 380 million years ago. Since then, countless lineages have evolved, some of which are in soil and others that are linked to insects. The ones associated with insects have adapted to different conditions than Streptomyces strains that are soil bound.
"It follows that if you look in a different evolutionary context, you find new chemistry," said Chevrette.
The researchers performed a huge number of experiments, testing how well the microbes could stop the growth of 24 fungi and bacteria. Some of those bacteria are known to be antibiotic-resistant.
"The real power in our study is that we did it 50,000 times," said Chevrette.
The researchers are hopeful that since cyphomycin was effective in their mouse model without causing side effects, it has the potential for use in the clinic. The team was not surprised by their findings. If these microbial compounds are safe for use around insects, that may help select for drugs that won’t harm people. These antibiotics may also have to function in environments where things are constantly adapting. They may, therefore, be better for treating antibiotic-resistant microbes.
"The insects are doing the prospecting for us," said Currie.
Learn more about why it's important to develop new antibiotics from the video above by the Royal Institution.