Many human medications can directly inhibit the growth and alter the function of the bacteria that constitute our gut microbiome . EMBL Heidelberg researchers have now discovered that this effect is reduced when bacteria form communities. In a first-of-its-kind study, researchers from EMBL Heidelberg's Typas, Bork, Zimmermann, and Savitski groups, and many EMBL alumni, including Kiran Patil (MRC Toxicology Unit Cambridge, UK), Sarela Garcia-Santamarina (ITQB, Portugal), André Mateus (Umeå University, Sweden), as well as Lisa Maier and Ana Rita Brochado (University Tübingen, Germany), compared a large number of drug-microbiome interactions between bacteria grown in isolation and those part of a complex microbial community.

Their findings were recently published in the journal Cell . For their study, the team investigated how 30 different drugs (including those targeting infectious or noninfectious diseases) affect 32 different bacterial species. These 32 species were chosen as representative of the human gut microbiome based on data available across five continents.

They found that when together, certain drug-resistant bacteria display communal behaviours that protect other bacteria that are sensitive to drugs. This 'cross-protection' behaviour allows such sensitive bacteria to grow normally when in a community in the presence of drugs that would have killed them if they were isolated. "We were not expecting so much resilience," said Sarela Garcia-Santamarina, a former p.