low concentrations ( less than or equal to 0.1 g/liter ) of eight amino acids ( methionine , leucine , valine , isoleucine , glycine , histidine , tryptophan , and tyrosine ) and of five vitamins ( pyridoxamine , p-aminobenzoic acid , biotin , nicotinic acid , and thiamine ) were also essential for biosynthesis .
C0002520
amino acids
C0017890
glycine