2,000 unknown bacteria species found in human gut

London: Researchers have identified almost 2,000 unknown bacterial species in the human gut, an advance that could help understand human health better and even guide diagnosis and treatment of gastrointestinal diseases.

The bacterial species discovered by researchers at European Molecular Biology Laboratory and the Wellcome Sanger Institute in the UK are yet to be cultured in the lab. The team used a range of computational methods to analyse samples from individuals worldwide. The results, published in the journal Nature, demonstrate that although researchers are possibly getting closer to creating a comprehensive list of microbes common in the microbiomes of North American and European people, there is a significant lack of data from other regions of the world.

The human gut is home to many species of microbes, collectively referred to as the gut microbiota. Despite extensive studies in the field, researchers are still working on identifying the individual microbial species that live in the gut and understanding what roles they play in human health. There are many reasons that some microbial species among the gut microbiota have remained unknown for so long, such as a low abundance or an inability to survive outside it. By using computational methods, researchers were able to reconstruct the genomes of these bacteria.

"Computational methods allow us to understand bacteria that we cannot yet culture in the lab," said Rob Finn from the European Molecular Biology Laboratory. "Using metagenomics to reconstruct bacterial genomes is a bit like reconstructing hundreds of puzzles after mixing all the pieces together, without knowing what the final image is meant to look like, and after completely removing a few pieces from the mix just to make it that bit harder," said Finn. The research highlighted the composition of gut bacteria differences between people around the world, and how important it is for the samples under study to reflect this diversity.

"We are seeing a lot of the same bacterial species crop up in the data from European and North American populations," said Finn. "However, the few South American and African datasets we had access to for this study revealed significant diversity not present in the former populations," he said. "Computational methods allow us to get an idea of the many bacterial species that live in the human gut, how they evolved and what kind of roles they may play within their microbial community," says Alexandre Almeida, postdoctoral fellow at Wellcome Sanger Institute.

In the study, the researchers leveraged the most comprehensive public databases of gastrointestinal bacteria to identify bacterial species that have not been seen before. "Research such as this is helping us create a so-called blueprint of the human gut, which in the future could help us understand human health and disease better and could even guide diagnosis and treatment of gastrointestinal diseases," said Trevor Lawley, group leader at the Wellcome Sanger Institute.