Friday, 10 April 2020

Reviewing how bacteria collaborate to cheat death

Antibiotics can make easy work of infections. But how do they affect the complex ecosystems of friendly bacteria that make up our microbiome?

New work led by Ludington and Stanford University's K.C. Huang set out to answer this challenging question and discovered a new form of antibiotic tolerance.

This is one of several research fronts on which Ludington uses the fruit fly microbiome to understand interactions between species in a bacterial community. It poses an ideal environment for probing both natural bacterial populations and the human microbiome.

The human microbiome is an ecosystem of hundreds to thousands of microbial species living within our guts. It affects our health and even our longevity. But it's difficult to elucidate the myriad ways that the different species that comprise our microbiome interact with and influence each other, even under normal conditions. Once antibiotics are introduced, little is understood about how these vital communities are impacted on a biochemical level.

This is why the fruit fly makes such an excellent model. Unlike the human microbiome, it consists of only a handful of bacterial species.

The simplicity of the fruit fly microbiome makes it the perfect vehicle for revealing how this multi-species biochemical interplay is altered by the introduction of antibiotics.

The researchers demonstrated that when a type of bacterium from the fruit fly microbiome, called Lactobacillus -- which are also found in yogurt -- is grown together with a vinegar-producing fly bacterium called Acetobacter, it is less susceptible to death by antibiotics.
This is a newfound category of a phenomenon called antibiotic tolerance, meaning that cells die much more slowly when found together than they would on their own. Tolerance can be dangerous, because this delay increases the risk that full-on resistance to the antibiotic could evolve.

It turns out that the Acetobacters consume the lactic acid that is excreted as a waste product by neighboring Lactobacillus, providing a fitness advantage to both species and triggering the tolerance the team discovered.

The team's work shows that the microbiome can be an important tool for understanding the relationships within communities of bacteria in the natural world on a biochemical level.

Studying the principles governing species-species interactions are key to understanding so much about ecosystems large and small and the microbiome is a critical tool for exploring these questions.


Andrés Aranda-Díaz, Benjamin Obadia, Ren Dodge, Tani Thomsen, Zachary F Hallberg, Zehra Tüzün Güvener, William B Ludington, Kerwyn Casey Huang. Bacterial interspecies interactions modulate pH-mediated antibiotic tolerance. eLife, 2020; 9 DOI: 10.7554/eLife.51493

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (

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