PREFERENTIAL SYNTHESIS OF EXTRACELLULAR PROTEASE BY ASPERGILLUS NIGER IN SULFUR DEFICIENCY

Abstract

The preferential synthesis of acid protease by Aspergillus niger mycelium in sulfur-deficiency was studied with special reference to the synthesis of cellular protein.
During sulfur-deficiency, the synthesis of protease occurred preferentially but that of cellular protein (including acid phosphatase) did not, whereas in nitrogen-deficiency neither the former nor the latter occurred.
Estimations of the amount of the amino acid pool and soluble protein fractions in mycelia and chasing of the radioactivities of these fractions of mycelia previously labeled with tracers showed that the amino acid pool together with the sulfur pool inherited from the previous culture seemed to be utilized, if at all, for the synthesis of cellular protein either in the presence or absence of sulfur source.
When the specific radioactivities of protease produced from mycelia previously labeled with ¹⁴C-amino acids were estimated, it was strongly suggested that in sulfur-deficiency exogenous amino acids were incorporated into protease protein via pool amino acid.