FIG 1.

S. venezuelae developmental stages. Colony morphology (left) and scanning electron micrographs (right) are shown. During the vegetative growth phase, hyphae form a dense mat of filaments on and in the substrate and the colony appears bald and shiny. The emergence of aerial hyphae marks the beginning of morphological and physiological differentiation and results in a fuzzy and white colony phenotype. In the course of sporulation, multigenomic aerial hyphae differentiate into 50 to 100 unigenomic prespore compartments, which mature into dormant exospores. The synthesis of a polyketide pigment during spore maturation gives the final S. venezuelae colonies a characteristic green color.