Thiago Monteiro Araújo dos Santos finds the invisible world of microbes captivating. By figuring out how bacteria build their outer walls, he hopes to inhibit the process. Such interference may ultimately lead to new ways to stop deadly infections. Santos aims to uncover how some bacteria’s cellular machinery manufactures and installs stabilizing protein “bricks” into cell walls. Weakening these walls could one day form the basis of new antibiotics, a development that could thwart antimicrobial resistance.