The production of conidiophores and conidia by newly germinated conidia of Aspergillus niger (microcycle conidiation).

The ability of Aspergillus niger conidia to produce conidiophores after germination in shaken culture at 30° was stimulated by the inclusion of glutamate in the medium. Incubation of the conidia at 35° to 41° increased swelling of the conidia and also the proportion which produced conidiophores. Although conidio-phore initiation was stimulated at temperatures between 35° and 41°, maturation was poor and optimum conidiation was obtained by incubation at these temperatures followed by 30°. Conidiophore formation from conidia required a prior period of spore metabolism and at temperatures between 30° and 41° did not occur until several hours after germination. Direct conidiophore production from conidia in the complete absence of vegetative growth was achieved by incubation of the conidia at 44° (which allows only swelling) for a prolonged period (48 h.) followed by 30°. Although vegetative growth was absent the conidiophores were similar to, but smaller than, normal subaerial conidiophores and viable conidia were produced. These conidia differed from subaerial spores in lacking the dark pigmented spore coat.