Fig. 2: Effects of iron competition between S. coelicolor and M. xanthus on actinorhodin production.

a Effects of myxochelin A in pure S. coelicolor cultures on actinorhodin production. b Actinorhodin production by S. coelicolor cultured on CTT agar medium with cell-free extracts of pure-cultured M. xanthus and cocultured M. xanthus. c Effects of physical separation during cocultures using cellophane disks on activation of actinorhodin biosynthesis. d Extracellular iron levels remaining in medium after culture. Empty: CTT agar plate without any cell inoculation, cultured under same conditions as other samples; <1 μM: the amount of iron remaining in the medium after culture was lower than the detection limit. Error bars indicate s.d. of three biological replicates. e Myxochelin production of pure-cultured M. xanthus under iron-restricted conditions. Error bars indicate s.d. of three biological replicates. f Changes in myxochelin production during coculture according to iron concentration. Error bars indicate s.d. of three biological replicates. g Intracellular iron levels in M. xanthus, normalized to the OD_600nm of each sample. Error bars indicate s.d. of three biological replicates. h Intracellular iron levels in S. coelicolor, normalized to the weight of each sample. Error bars indicate s.d. of three biological replicates. i Actinorhodin production during coculture according to the iron concentration. Total actinorhodin was extracted from cells and medium and treated with KOH. Absorption at OD_640nm indicated actinorhodin production. Error bars indicate s.d. of three biological replicates. j Actinorhodin production by pure-cultured S. coelicolor under iron-restricted conditions. The upper four colonies were cultured on CTT medium treated with 2,2′-bipyridyl. The lower four colonies were cultured on CTT medium treated with 350 μM 2,2′-bipyridyl and additional iron. Co coculture, Pure pure culture, Sc S. coelicolor, Mx M. xanthus.