| Popis: |
Summary Two strains of Streptococcus lactis , one of Streptococcus cremoris , and one of Streptococcus lactis var. maltigenes were shown to possess peptidases capable of hydrolyzing a number of commercially available dipeptides and two tripeptides into the constituent amino acids. The four test cultures exhibited similar hydrolytic ability toward the peptides under examination. If the C-terminal amino acid of the peptide was of d configuration, no hydrolysis occurred. Dipeptides in which one of the constituent amino acids was l-Ieucine or l-valine, when substituted for these amino acids in chemically defined media, were shown to fulflll the nutritional requirements of each of the four cultures for these essential acids. S. lactis var. maltigenes degraded the freed leucine and valine from such peptides to 3-methylbutanal and 2-methylpropanal, respectively. The possible role of peptides as precursors of flavor compounds in dairy products is discussed. |
