Fig. 3

Spore-inducing activity of diacetonamine and its amide derivatives toward B. amyloliquefaciens AHU 2170. Sporulation after the treatment with 40 and 400 µM is shown in microscopic photographs. Spores are apparent as short rods stainable as green by SYTO 9. Photo-images are after 48-h incubation upon exposure to the test compounds in MSG medium under a fluorescent microscope. Sporulation frequency was defined as (±), ambiguously positive as less than 10% sporulation from all the vegetative cells; (+), weakly positive as 10–50% sporulation; and (++), positive as >50% sporulation. Scale bar = 5 μm