Chemical and biological features of endofungal bacteria.

(A) Chemical structures of rhizoxin, an antimitotic macrolide, and rhizonin A, a hepatotoxic cyclopeptide. (B) Light micrograph of a sporangium of R. microsporus (ATCC 62147) stained with a viability assay system (Invitrogen). Green spots are living cells of the bacterial endosymbiont B. rhizoxinica. (C) Life cycle of R. microsporus strains and their endosymbionts B. rhizoxinica and B. endofungorum. Endobacteria are propagated within fungal spores (vertical transmission). Under laboratory conditions, isolated bacteria can infect compatible host strains (horizontal transmission).