Biochemical aspects on the germination of conidiospores of Aspergillus niger

Summary

Biochemical events occurring in synchronously germinating spores of Aspergillus niger strain 1617 were investigated. The spores were found to require l-proline (or l-alanine), glucose and phosphate for the complete germination. The germination process in the above synthetic medium could be divided into three phases: endogenous swelling, exogenous swelling and sprouting. The first swelling phase was not influenced by the severe environmental factors so far tested, while the second phase was found to be affected by them, especially the CO₂ concentration. Rates of increase in cellular substances and in consumption of environmental substances changed markedly after germ tubes sprouted. The first cellular synthesis thus far detected was nucleic acid synthesis in the exogenous swelling phase. At the end of this phase accumulation of free amino acids, mainly glutamic acid and alanine, was observed. Protein synthesis then followed. A conspicuous increase in O₂-uptake commenced in parallel with the active synthesis of protein, when germ tubes began to sprout.

During the course of germination a shift of metabolic pattern from that of the spore to the mycelium was indicated by the ratios of total nitrogen/dry weight, RNA/DNA, oxygen consumed/glucose consumed, and oxygen consumed/total nitrogen taken at various time intervals.