Gut bacteria composition affects nutritional choices

Two new studies have revealed that the gut bacteria composition affects nutritional choices as well as reproduction, using common fruit flies as a model system. 

The discoveries provide an exciting illustration into how microbes in the gut can influence host animals, which could be important for understanding the effects of the gut microbiota on physiology and cognitive function in humans in the future.

“Beyond the biomedical significance of this research, there are potential interesting applications in the context of invasive and pest species control,” said Dr Fleur Ponton, the last author on both studies. Dr Ponton is based at Macquarie University’s Department of Biological Sciences.

Co-authored by researchers from Macquarie’s Department of Biological Sciences and the University of Sydney’s Charles Perkins Centre, the studies report that that the gut microbiota of the common fruit fly has a significant effect on their foraging behaviour and reproductive success, and that its influence can be carried down to the next generation.

Published in Current Biology, the study into foraging behaviour manipulated the type and timing of bacteria individual flies were exposed to, and examined their olfactory-guided preferences to food microbes and nutrients.

In addition to foraging for nutrients to achieve a balanced diet, the researchers found flies also forage for bacteria to populate a healthy gut flora. Responding to smells associated with particular bacteria in foods, the flies showed a distinct preference for more beneficial types of bacteria over less beneficial types or food lacking the bacteria. These responses were influenced by bacteria already present in the gut.

In a separate study, published in Biology Letters, researchers inoculated flies with different types of bacteria to observe the consequences of changes in the gut bacteria composition of sexually interacting fruit flies.

They found the reproductive investment and success of a mating pair was influenced by gut bacteria, as well as the body mass of offspring.

Lead author Dr Juliano Morimoto, now at Macquarie University, said the findings reveal the effect of gut microbiota on reproduction and also suggest these effects can be carried over to the next generation.

“Given the importance of the gut microbiota in physiology and health, our findings reveal important and long-lasting effects of gut bacteria on reproduction and offspring traits,” he said.

“As understanding of the gut microbiome and its effect increases, the potential for breakthroughs in understanding broader health impacts increases too.”

Professor Stephen Simpson, academic director at the Charles Perkins Centre and a co-author on both papers, said, “This demonstration that bacteria in the gut influences foraging and reproductive behaviour is of particular interest for further research.”