CARBON DIOXIDE FIXATION IN GERMINATING CONIDIOSPORES OF ASPERGILLUS NIGER

Abstract

Incorporation of ¹⁴CO₂ into conidiospores of Aspergillus niger (strain 1617) was investigated under various cultural conditions.
The conidia incubated in a complete germination medium incorporated ¹⁴CO₂ very actively without any lag period. By using various media for incubation, it was found that the more favorable the medium for the germination, the more active was the ¹⁴CO₂-incorporation. In the germinating conidia fed with ¹⁴CO₂, a large amount of radioactivity was found in the protein fraction as well as in the acid-soluble fraction, in which ATP was revealed to be one of the major substances to be labeled within a short period. Quickly labeled were also nucleic acids, in which adenine, cytosine and uracil were strongly labeled, while thymine and guanine were less strongly, but definitely, labeled even at the onset of germination.
Based on these observations as well as those made earlier of the phosphorus and alanine metabolisms of germinating conidia, inferences and discussions were made of the biochemical events occurring in the early phase of conidia germination.