Table 1.

Amino acids, peptides, and proteins tested as growth substrates for strain A3 in tap water at 15°C^a

Amino acid	Peptides and proteins
l-Alanine	l-Alanyl-l-alanine
l-Aspartate	l-Alanyl-l-glutamine
l-Glutamine	Glycyl-l-aspartate
l-Glutamate	l-Glutamyl-l-glutamate
Glycine	Glycyl-l-leucyl-l-tyrosine
l-Isoleucine	Poly-dl-alanineb
l-Leucine	Poly-l-aspartateb
l-Lysine	Poly-l-glutamateb
dl-Phenylalanine	Caseinc
l-Proline	Gelatinc
dl-Serine	Lectinc
l-Threonine
l-Tyrosine
l-Valine

^aAll compounds were tested individually; the peptides and proteins were also tested simultaneously as constituents of the peptide-and-protein mixture.

^bMolecular masses: poly-dl-alanine, 1 to 5 kDa; poly-l-aspartate, 5 to 15 kDa; and poly-l-glutamate, 3 to 15 kDa (Sigma-Aldrich, Germany).

^cCasein sodium salt from bovine milk; gelatin from bovine skin, type B; and lectin from Canavalia ensiformis (jack bean) (Sigma-Aldrich, Germany).