The first culture studies that expl

The first culture studies that explored the gut microbiota were performed as early as the 1970s42 and studied how diet can influence the composition of the gut microbiota43. Interestingly, these early studies observed that some bacteria are associated with cancer44, as suggested later32. Overall, Enterobacteriaceae and Veillonellaceae families were the most common among the 400 different cultured species from the human gut microbiota during the 1970s45. At that time, the normal microbiota was thought to be dominated by non-spore-forming, anaerobic, rod-like bacteria. Interestingly, many of the dominant species that were identified in 1995 (ref.46) correspond to the same dominant species that were subsequently detected by metagenomics47.