Previous work has shown that certain bacterial species are transferred from parents to children. A new study from the Max Planck Institute in Tubingen suggests that part of your microbiome is actually inherited. That is, there are specific genes that regulate which bacteria thrive. To come to that conclusion, scientists correlated genetic variations to bacterial species in 1126 pairs of twins, both identical and fraternal. They found dozens of species that, while environmentally acquired, propagate due to genetics. These include species involved in gastrointestinal disorders, blood pressure regulation and autoimmunity.
It is well understood that many microbial species release amino acids and vitamins into the environment to benefit the population. However, this behavior could be harmful if “outsider” species receive these molecules without contributing to the group. Scientists at the Max Planck Institute have observed the answer to this problem in biofilms. Using directed mutations, computer modeling and mass spectrometric imaging they created a new approach called “synthetic ecology”. Using this approach they found that “cooperating” bacteria create clusters and physically exclude “non-cooperating” bacteria. Notably, bacteria in liquid culture show no exclusion mechanisms. Given the significant health issues associated with bacterial biofilms, insight into their formation and persistence are crucial.
The role of gut bacteria has been well-established for diseases such as inflammatory bowel disease, diabetes and Alzheimer’s and has even been shown to play a role in depression, infertility, alcoholism and HIV progression. Starting in 2013, the US FDA began to regulate fecal transplantation as a way to re-establish healthy gut microbiota to patients with gastrointestinal disease or who have had their normal bacterial flora disrupted by antibiotics. These procedures has shown tremendous potential (reviews HERE and HERE). Recently, scientists from the Wellcome Trust Sanger Institute grew and catalogued 137 bacterial species, many previously “unculturable”, from the guts of healthy patients. This work will lay the foundation to determine the role that specific bacteria play in specific diseases as well as determining a proper combination of species required for treatment, potentially allowing fecal transplantation to be replaced by defined, active cultures in pill form. Additionally, for the first time this work demonstrated that 50-60% of bacteria in the intestinal microbiota for resistant spores, allowing for host-to-host transmission.
Direct liver cell damage by alcohol has been well established as one of the primary causes of liver disease. Recent work by scientists at UC San Diego demonstrates that, in addition, alcohol can lead to liver disease by causing an imbalance in the gut microflora. Humans produce two natural broad-spectrum antimicrobial proteins called REG3B and REG3G that surveil gut mucosal bacteria and prevent overgrowth. Alcohol causes a down-regulation in the genes encoding for REG3B and REG3G leading to bacterial overgrowth, an increase in microbial translocation, immune activation and further cell damage, including the liver. Mice with REG3B/REG3G knockouts have more severe liver disease while mice with REG3G over-expression avoid liver damage. This work adds to the increasing importance of gut health on a wide range of disease.
Last Friday the White House announced that it was creating a National Microbiome Initiative to bring together scientists to study microbial diversity associated with the human body and our environment. The move will inject $121 million/year into microbiome projects from federal agencies as well as an additional $400 million from other institutions, including the Gates Foundation. In addition to monetary support, the NMI will foster collaborative studies, interdisciplinary research and comparative studies.