Figure 1.

Black yeast symbiont associated with fungus-growing ants. (a) Photo of a black yeast colony growing on nutrient agar. (b) Photo of Apterostigma pilosum, a fungus grower from which black yeasts are isolated. (c) Black yeast growth on ant body parts. Black yeast is most frequently isolated from ant thoraxes. (d) Black yeast growth on thorax surfaces. Black yeast growth is concentrated on the metapleura (ventral) surface of the thorax. (e) Scanning electron micrograph of A. pilosum thorax (metapleura) on which antibiotic-producing Pseudonocardia and black yeasts grow; Pseudonocardia seen here as white tufts on the ants' cuticle. CFUs, colony forming units.