JAN 22, 2017 10:04 AM PST

Moth gut microbe makes antibiotic

WRITTEN BY: Kerry Evans

Can insects get infected with bacteria?

 

Sure they can, but it doesn’t happen all that often. That fact sparked the interest of researchers at Zhejiang University and the Max Planck Institute for Chemical Ecology.

 

The cotton leafworm, Spodoptera littoralis, is a moth, and its larvae love to munch on plants. Bacteria also hang out on plants, and the larvae inevitably ingest them. The odd thing is that these bacteria don’t seem to make the little larvae sick.

 

Spodoptera littoralis larva

 

This led Yongqi Shao and Wilhelm Boland to look at the larvae’s gut bacteria - maybe their microbiome was helping to keep them healthy?

 

They found that the composition of gut bacteria changes as these little insects grow up. Younger larvae have many virulent Enterococcus species in their guts, but older larvae have the nonpathogenic E. mundtii. According to Shao, "we show that the evolutionary success of insects is partially based on a symbiotic association with gut microbes, which co-evolved with their hosts over millions of years."

 

The group Isolated various species of Enterococcus from the larvae and determined how they competed with each other. What they found was quite surprising - E. mundtii inhibited the growth of other bacteria! How, exactly? They showed that E. mundtii secretes a bacteriocin (an antimicrobial peptide) that they called mundticin KS. Bacteriocins are small proteins made by bacteria to inhibit the growth of other closely related bacteria.

 

In their first experiment, they showed that something in the E. mundtii culture supernatant (later identified as mundticin KS) was able to inhibit the growth of E. faecalis or E. casseliflavus. It did not inhibit the growth of other E. mundtii cells - it is immune to the mundticin that it produces.

 

Shao and Boland went on to test if mundticin could cure larvae of a bacterial infection. They purified mundticin and infected the larvae with a high dose of E. faecalis. Sure enough, larvae that had E. mundtii in their guts, that also made mundticin, were cured of the infection.

 

According to Boland, “the antimicrobial promotes symbiosis by providing a competitive advantage for E. mundtii, contributing to its dominance in the gut microbiome, while protecting the cotton leafworm against pathogens. We expect that protective associations with antibiotic-producing bacteria is a common strategy of insects against microbial invaders."

 

The next step is to look for similar antimicrobial mechanisms in other insect species. Such systems could be exploited by the agriculture industry to protect crops from pathogens. These peptides could also be useful to human health, where some suggest they could be used as food preservatives.

 


Source: Cell Chemical Biology, EurekAlert

About the Author
  • Kerry received a doctorate in microbiology from the University of Arkansas for Medical Sciences.
You May Also Like
DEC 17, 2019
Cannabis Sciences
DEC 17, 2019
Overhauling the Endocannabinoid System with High-fat, High-sugar Diet
If both the endocannabinoid system and the intestinal microbiome are affected by dietary consumption habits, wouldn’t it be reasonable to suggest tha...
DEC 28, 2019
Microbiology
DEC 28, 2019
A DNA Star That Can Detect Dengue Virus
Like origami paper, DNA molecules can be folded and arranged into complex three-dimensional structures....
DEC 30, 2019
Microbiology
DEC 30, 2019
Understanding How Microbes in the Body Function as a Community
Advances in genetic technologies made it possible for researchers to learn more about the vast community of microbes that resides in the human body....
JAN 17, 2020
Cardiology
JAN 17, 2020
Eating Walnuts Reduces Risk for Heart Disease
Walnuts may be more than just a tasty snack. Researchers from the University of Pennsylvania have found that they may also promote healthy gut bacteria, wh...
JAN 19, 2020
Genetics & Genomics
JAN 19, 2020
Engineering Mosquitoes to Stop Dengue Virus Transmission
The dengue virus is transmitted by mosquitoes. It is found in over one hundred countries and threatens three billion people with a serious illness....
FEB 10, 2020
Immunology
FEB 10, 2020
Measles infections can give the immune system amnesia
The immune system detects the presence of invading microbes that it recognizes from previous infections, and initiates a full-blown immune response. New re...
Loading Comments...