ALANINE METABOLISM IN CONIDIOSPORES OF ASPERGILLUS NIGER IN THE EARLY PHASE OF GERMINATION

Abstract

Since spores of Aspergillus niger require L-alanine specifically for the initiation of germination, the role of alanine in this respect was investigated using alanine-C¹⁴ as a tracer. The radioactive alanine was actively incorporated into spores during germination after a short lag of about 30min. The alanine once incorporated was immediately deaminated resulting in the formation of ammonia and pyruvate, which in turn was gradually decarboxylated with the evolution of CO₂.
The radioactivity of incorporated alanine-C¹⁴ was readily distributed to various fractions of germinating spores, especially to protein and nucleic acids. In this case, pyruvate, CO₂ and probably ammonia derived from alanine seem to supply building blocks for the construction of these macromolecular substances in the early phase of germination. The observation that the base composition of ribonucleic acid changed markedly in the early germination implies that those metabolites of alanine involve in the modification of nucleic acid molecules; such event occurring in the early phase is considered to be a prerequisite for the initiation of germination.