Our laboratory studies persister cells and uncultured bacteria. Persisters are dormant variants of regular cells which are tolerant to antibiotics and responsible for recalcitrance of biofilm infections. Using transcriptome analysis, cell sorting and whole genome sequencing we are identifying genes responsible for persister formation. We identified a number of mechanisms for persister formation, and the first compound that kills them, acyldepsipeptide. Uncultured bacteria make up the majority of species on the planet, but do not grow in the lab. We developed a general method to grow these organisms by cultivation in their natural environment. In marine sediment, siderophores from neighbors serve as growth factors for uncultured bacteria. We have recently identified growth factors for uncultured bacteria from the human microbiome. We also use uncultured bacteria as a source for discovering new antibiotics.