It is a matter of whether we allow microbes to enter the food chain.

Abstract

When Martin Loessner decided as a little boy to become a scientist, he was already showing a lot of resistance. Even during Carnival—the so-called ‘Fifth Season’ in the western parts of Germany celebrated with street parades and costume balls—he gave his mum ‘a hard time finding costumes to dress him (me) up as a researcher or explorer’. Since then, Martin followed his curiosity and studied biology in Freiburg i. Br., Germany, and Michigan, USA, and eventually embarked on a PhD at the Bacteriological Institute at the Technical University in Munich, Germany. Here, he further stayed as a postdoctoral researcher, habilitated and became an Assistant Professor. During his early research years, he discovered his passion for bacteriophages and how they interact with their bacterial hosts. Especially, the function of the bacterial cell envelope in the uptake and release of bacteriophages fascinated him and he was at the forefront of research into endolysins (Loessner et al. 1995). These enzymes are encoded by the bacteriophage and activated at the end of the phage multiplication cycle. At that stage, new phage particles are assembled inside the bacterial cells and the bacteria start producing endolysins. With that, they decide their own fate: the endolysin recognizes the peptidoglycan of the bacterial envelope while its catalytic domain hydrolyses the cell wall from within. Together with a membrane pore-forming holin, endolysin activity destroys the host bacterium to release the newly produced phage particles (Loessner et al. 1997). Having found ‘a new agent that works as an antimicrobial, the next question you ask is: What about resistance?’. The answer to that question was unexpected. Since endolysins target highly conserved bonds within the cell wall (Korndörfer et al. 2006), bacteria are essentially unable to modify them, which prevents them from developing resistance. As any microbiologist can imagine, the discovery of a lack of resistance to an effective antibacterial agent can be mind-blowing. So, Martin had to withstand opposing opinions from many researchers and colleagues from the field. However, up to this day, it seems to be worth the effort; researchers have not been able to find any stable bacterial resistance mechanism to endolysins. Applying phages to improve lives