The gut microbiome is a complex, interconnected ecosystem of species. And as in any ecosystem, some organisms are predators and others are prey. A new study conducted by researchers at Brigham and Women\u2019s Hospital and the Wyss Institute examines the effects of bacteriophages\u2014viruses that infect and kill bacteria. They found that phages can have a profound impact on the dynamics of the gut microbiome by not only directly affecting certain species, but also creating a cascading effect on others. Phages can also affect their human host by modulating metabolites, including chemical substances found in the brain. The team includes first author Bryan Hsu and corresponding senior author Pamela Silver of the Wyss Institute, as well as Dr. Lynn Bry of Brigham and director of the Massachusetts Host-Microbiome Center, Cell Host & Microbe. <\/p>\n
\u201cOne of the main interests in my lab is understanding changes in gut microbiome dynamics. Bacteriophages are a major component of the microbiome, but have not yet been studied much,\u201d said Dr. Gerber, PhD, MPH, co-director of the Massachusetts Host-Microbiome Center and head of the Division of Computational Pathology in the Department of Pathology at Brigham. \u201cSome people are researching phage therapy and using phages to kill microbes, but phages also occur naturally in the gut and coexist with the rest of the ecosystem. We wanted to find out what they do there.\u201d<\/p>\n
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 analyses, the team found that the phages caused attrition of the species they preyed on, as expected, but with a ripple effect on the rest of the ecosystem, including blooms of non-target species. <\/p>\n
In addition to examining the effects on microbes, the team also investigated the effects on the metabolome\u2014chemical substances that can originate from both the host and the bacteria present. They found that when modulating the microbiome with phages, they could detect targeted changes in the metabolome, including changes in neurotransmitter levels and bile acids. <\/p>\n
\u201cI find this result fascinating to follow up on, and it raises important questions: Can we use phages to modulate these activities? Could this be an intervention for conditions such as depression, where you want to change neurotransmitter levels?\u201d said Gerber. \u201cEven if they are not used as a direct therapeutic, our study suggests that phages can be a useful tool for understanding the potential effects of other therapeutics that alter the microbiome.\u201d <\/p>\n
Gerber and his colleagues are particularly interested in investigating the interface between phages and malnutrition in developing countries, as malnutrition can have profound effects on the metabolome and the microbiome.<\/p>\n
\u201cWe hope that our work provides a framework for future studies to investigate the interplay between phages, microbiota, and the host\u2019s health and disease,\u201d said Gerber.<\/p>\n
Source: https:\/\/phys.org\/news\/2019-06-phage-bacteria-predators-gut-microbiome.amp<\/a><\/p>\n