The substrate constant for the ammonium ion of growing Saccharomyces cerevisiae

The relation between ammonium concentration and growth rate was studied in steady state continuous cultures of Saccharomyces cerevisiae in nitrogen-limited glucose ammonium medium. This relation could be described by the Monod equation. A maximum specific growth rate of 0.41 h-1 and a substrate constant for ammonium of 5-11 muM were calculated. Ammonium was determined by a modification of the phenol hypochlorite method. A discussion of the results in view of literature data on the substrate constants for other nutrients is given.