Autoagglutination of 042 and mutants in L-broth. L-broth cultures were grown overnight at 37°C with shaking, then permitted to settle undisturbed at room temperature for 1 hour. (a) Broth cultures revealing a pellet at the bottom of the culture tube correlating with autoagglutination of bacterial cells. (b) Transmission electron microscopy of 042 and 042aap cultures. Ten microliters of L-broth cultures from a were withdrawn prior to incubation on the bench-top and processed for negative staining. Bars, 1 μm.