UTILIZATION OF AMINO ACIDS BY RHIZOPUS NIGRICANS

Abstract

Growth and sporulation cycles of Rhizopus nigricans were compared using 23 amino acids and 2 inorganic compounds as nitrogen sources.When supplied individually, all monoamino-monocarboxylic acids supported growth. Heaviest mycelium was obtained from arginine, glycine, ornithine, or alanine. No growth was observed in lysine, cystine, cysteine, tyrosine, dihydroxy-phenylalanine, histidine, or tryptophan. When the amino acids were supplied as a mixture by a process of single elimination, most rapid germination occurred in the absence of valine or aspartic acid. Greatest initial growth was observed when arginine, lysine, aspartic acid, or leucine were omitted. Most profuse growth after a period of 15 hours was noted in the absence of cystine, serine, or aspartic acid. Earliest sporulation took place when aspartic acid, tyrosine, threonine, or dihydroxyphenylalanine were omitted. Organisms produced an acidic reaction in the media which retarded growth considerably,Unexplained similarities between germination–sporulation responses observed and those reported for the genus Bacillus may be of interest or significance.