We've updated our Privacy Policy to make it clearer how we use your personal data. We use cookies to provide you with a better experience. You can read our Cookie Policy here.


Bees Nourish Their Own Gut Bacteria

A bee.
Credit: Leandro fregoni/Unsplash
Listen with
Register for free to listen to this article
Thank you. Listen to this article using the player above.

Want to listen to this article for FREE?

Complete the form below to unlock access to ALL audio articles.

Read time: 2 minutes

Bees can synthesize compounds to sustain their own gut bacteria, according to a new study.

Published in Nature Microbiology, the research found that the guts of bees fed on a simple sugar water diet can be colonized by Snodgrassella alvi bacteria – despite the fact that this species can’t metabolize sugar to grow.

The researchers from the University of Lausanne managed to explain this odd observation by directly measuring the gut metabolites of the bees. They found that compounds synthesized by the bees’ guts keep S. alvi thriving.

Busy bees

Bees, just like humans, can home a variety of bacteria in their guts. This housing has mutual benefits; the microbes receive a habitat, and the host gets help processing food and absorbing nutrients.

Most of the 20 bacteria species that can live in the guts of honeybees feed on pollen. S. alvi, however, can’t do so as it lacks a functional glycolysis pathway.

So, one might wonder, why is the microbe drawn to inhabit the guts of honeybees when it can’t feed off sugar?

To answer the question, a group of Lausanne researchers first began by feeding a group of bees one of two diets: a simple one (sugar water) or a complex one (sugar water and pollen). They then inoculated the bees with S. alvi and other strains of Gilliamella bacteria and waited to see how the microbes would fare.

Surprisingly, the team found that the simple sugar water diet was sufficient for S. alvi to colonize the honeybee gut and thrive.

To explain this curious finding, the researchers proposed a hypothesis: the bees’ guts directly provide S. alvi with the necessary nutrients to live.

To test this theory, the researchers used gas chromatography-mass spectrometry (GC-MS) to analyze the metabolites extracted from the bees’ guts. Even in the guts of bees that had only been fed sugar water, the researchers found high levels of citrate – a compound found in lower quantities in pollen-fed bee guts.

“We observed that some substrates for S. alvi are classic degradation products from amino acid catabolism (i.e. urea, kynurenine, 3-hydroxy-3-methylglutarate), while others are carboxylic acids derived from respiration of sugars (i.e. citrate, malate),” Dr. Andrew Quinn, a microbiome scientist at the University of Lausanne, told Technology Networks. “Some substrates for S. alvi are de-novo synthesized from glucose while others are metabolized from essential compounds in the diet.”

Quinn and his colleagues thus assumed that the guts of bees fed on sugar water synthesized citrate and other compounds for the S. alvi to consume.

“An elegant feature of our experimental design was to restrict the bees to sugar water only diets in multiple experiments,” Quinn added. “This allowed us to see that even compounds that could not be synthesized from sugar metabolism were continuously released back into the gut by the bee.”

To confirm this idea, the team then sought help from a neighboring lab at the Swiss Federal Institute of Technology Lausanne (EPFL). By using the nanoscale secondary ion mass spectrometer at the lab – one of the few such instruments in Europe – and by feeding bees glucose diets laced with carbon isotope atoms, the team could observe that the citrate and other S. alvi substrates in the bees’ guts were enriched with carbon isotopes; other compounds that aren’t S. alvi substrates, such as kynurenine, weren’t enriched.

These findings seemingly proved that the bees were converting their dietary glucose into S. alvi substrates.

“By exporting bacterial substrates into the gut, the bee may profit in multiple ways,” Quinn posited. “1) using its microbiota to efficiently recycle valuable nutrients 2) using the microbiota to degrade toxic metabolites 3) using the gut microbiota to synthesize essential nutrients and 4) controlling the gut environment to favor the colonization of native symbionts as opposed to opportunistic pathogens.”

According to Quinn, the bees’ digestive mechanisms could also play a role in the insects’ vulnerability to climate change and pesticides.

“Their vulnerability could result from a disruption in this intricate metabolic synergy between the bee and its gut microbiota,” Quinn added. “We already know that exposure to the herbicide glyphosate makes bees more susceptible to pathogens and reduces the abundance of S. alvi in the gut. Now, armed with these new findings, we're looking for answers to these pressing questions.”


Reference: Quinn A, El Chazli Y, Escrig S, Daraspe J, Neuschwander N, McNally A, Genoud C, Meibom A, Engel P. Host-derived organic acids enable gut colonization of the honey bee symbiont Snodgrassella alviNat Microbiol. 2024. doi: 10.1038/s41564-023-01572-y