How Predators Influence Our Gut Microbiota: Bacteriophages
The gut microbiome is a complex and interconnected ecosystem of species. And, as in any ecosystem, some organisms are predators and others are prey. A new study by researchers at Brigham and Women’s Hospital and the Wyss Institute examines the effects of bacteriophages, viruses that infect and kill bacteria. They conclude that phages can have a profound influence on the dynamics of the gut microbiome, not only by directly affecting certain species but also by causing a cascading effect on others. Phages can also affect their human host by modulating metabolites, including chemicals found in the brain. The team includes first author Bryan Hsu and senior corresponding author Pamela Silver, both from the Wyss Institute, as well as Dr. Lynn Bry, from Brigham and Director of the Massachusetts Host-Microbiome Center, Cell Host & Microbe.
“One of the main interests of my lab is to understand changes in gut microbiome dynamics. Bacteriophages are an important part of the microbiome, but they have not yet been extensively studied,” said Dr. Ph.D., MPH, co-director of the Massachusetts Host-Microbiome Center and head of the Division of Computational Pathology in the Department of Pathology at Brigham. “Some people research phage therapy and use phages to kill microbes, but phages are also found naturally in the gut and coexist with the rest of the ecosystem. We wanted to find out what they do there.”
To answer this question, the team colonized the guts of mice with a defined set of human bacterial species and then added phages to track the growth of each microbe. Using high-throughput sequencing and computational analysis, the team found that phages caused the decline of the species they preyed on, as expected, but with a ripple effect on the rest of the ecosystem, including proliferations of non-target species.
In addition to investigating the effects on microbes, the team also studied the effects on the metabolome: chemicals that can come from both the host and the bacteria present. They found that by modulating the microbiome with phages, they could observe specific changes in the metabolome, including changes in neurotransmitter and bile acid levels.
“This finding fascinates me for further investigation and raises important questions: Can we use phages to modulate these activities? Could it be an intervention in diseases like depression, where you want to modify neurotransmitter levels?” said Gerber. “Even if not used as a direct therapeutic, our study suggests that phages can be a good tool for understanding the potential effects of other microbiome-modifying therapeutics.”
Gerber and his colleagues are particularly interested in studying the interface between phages and malnutrition in developing countries, as malnutrition can have profound effects on the metabolome and microbiome.
“We hope that our work provides a framework for future research examining the interplay between phages, microbiota, and host health and disease,” said Gerber.
Source: https://phys.org/news/2019-06-phage-bacteria-predators-gut-microbiome.amp
