A common bacterial species in both the human gut and biological laboratories is Escherichia coli, whose individual rod-like shapes can be seen here in extreme close-up and as tiny points of green light. The cells are flowing through a microfluidic chamber that allows researchers to observe how they respond to different concentrations of an antibiotic drug. Their dynamic responses reveal how bacteria in nature react when exposed to stresses and can help reveal the processes that lead to antibiotic resistance