There are numerous different scenarios in which microorganisms are exposed to highly reactive molecules known as free radicals. These molecules are capable of damaging important cell components and may be generated during normal cell metabolism or in response to environmental factors. Free radicals play a significant role in antibiotic effectiveness, the development of diseases and the normal functioning of the human immune system. A team of researchers from Charité – Universitätsmedizin Berlin has discovered a previously unknown mechanism which enables microorganisms to protect themselves against free radicals. Their findings may help improve the efficacy of antimicrobial substances.