S U M M A R YCarbon catabolism was studied during the synchronous development of conidiophores of Aspergillus niger. The activities of key enzymes of the Embden-MeyerhofParnas (EMP) and pentose phosphate (PP) pathways were measured and studies of 14C0, production from [ 1-14C]-and [6-14C]glucose were made. The enzyme activities together with the radiorespirometric studies showed that both the EMP and PP pathways were present and operative at all stages of conidiophore development but that the relative activities of the pathways differed. The highest activity of the EMP pathway occurred during the initial period of vegetative growth before any signs of morphological change, High EMP activity and high 6-C/1-C ratios were obtained in a medium which did not support conidiophore initiation but allowed vegetative growth to occur. In contrast, high activity of the PP pathway and very low 6-C/ I-C ratios accompanied each stage of conidiophore development. The results suggest that the PP pathway predominates during conidiophore development of this fungus.

Fluorometric methods have been used for the determination of the momentary levels of some glycolytic intermediates and adenylates during the development of Aspergillus niger in fermenter culture and also in a medium which allows vegetative growth but not conidiation. During periods of active glycolysis the levels of the hexose monophosphates were low while the other intermediates were high; during periods of low glycolysis this pattern was reversed. The interrelations of the momentary concentrations of the intermediates indicated that the phosphofructokinase step may be a control site in glycolysis in Aspergillus niger.

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