E-Mail IMAGE: In order to increase survival chances in contact to eukaryotic host cells, both symbiotic and pathogenic bacteria have developed methods to influence host cell behavior. The type III secretion system... view more Credit: Max Planck Institute for Terrestrial Microbiology Basic, acidic, basic again: for pathogenic bacteria such as Salmonella, the human digestive tract is a sea change. So how do the bacteria manage to react to these changes? A team of researchers from the Max Planck Institute for Terrestrial Microbiology in Marburg led by Andreas Diepold has now provided a possible explanation: pathogenic bacteria can change components of their injection apparatus on the fly - like changing the tires on a moving car - to enable a rapid response.