Affiliation:
1. Unité de Recherches Laitières et Génétique Appliquée1 and
2. Unité de Biochimie et Structure des Protéines,2 Institut National de la Recherche Agronomique, Centre de Recherches de Jouy-en-Josas, 78350 Jouy-en-Josas, France
Abstract
ABSTRACT
To study the substrate specificity of the oligopeptide transport system of
Lactococcus lactis
for its natural substrates, the growth of
L. lactis
MG1363 was studied in a chemically defined medium containing milk peptides or a tryptic digest of α
s2
-casein as the source of amino acids. Peptides were separated into acidic, neutral, and basic pools by solid-phase extraction or by cation-exchange liquid chromatography. Their ability to sustain growth and the time course of their utilization demonstrated the preferential use of hydrophobic basic peptides with molecular masses ranging between 600 and 1,100 Da by
L. lactis
MG1363 and the inability to use large, acidic peptides. These peptide utilization preferences reflect the substrate specificity of the oligopeptide transport system of the strain, since no significant cell lysis was inferred. Considering the free amino acid content of milk and these findings on peptide utilization, it was demonstrated that the cessation of growth of
L. lactis
MG1363 in milk was due to deprivation of leucine and methionine.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
46 articles.
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