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Specificity of milk peptide utilization by Lactococcus lactis
V Juillard1, A Guillot, D Le Bars
1Unité de Recherches Laitières et Génétique Appliquée, Centre de Recherches de Jouy-en-Josas, France. juillard@jouy.inra.fr
Applied and Environmental Microbiology
|April 18, 1998
Summary
Lactococcus lactis preferentially utilizes hydrophobic basic peptides for growth, not large acidic ones. Growth cessation in milk is due to leucine and methionine deficiency.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Lactococcus lactis is a key lactic acid bacterium used in dairy fermentation.
- Understanding nutrient uptake is crucial for optimizing fermentation processes.
- Oligopeptide transport systems play a vital role in bacterial nutrition.
Purpose of the Study:
- To investigate the substrate specificity of the oligopeptide transport system in Lactococcus lactis MG1363.
- To determine which milk peptides support the growth of L. lactis.
- To identify the limiting amino acids for L. lactis growth in milk.
Main Methods:
- Culturing L. lactis MG1363 in a defined medium with milk peptides or alpha s2-casein digest.
- Separating peptides into acidic, neutral, and basic pools using solid-phase extraction and cation-exchange chromatography.
- Monitoring bacterial growth and peptide utilization over time.
Main Results:
- L. lactis MG1363 preferentially utilized hydrophobic basic peptides (600-1,100 Da).
- Large, acidic peptides were not utilized by L. lactis MG1363.
- Growth cessation in milk was linked to the depletion of leucine and methionine.
Conclusions:
- The oligopeptide transport system of L. lactis exhibits specificity for certain peptide types.
- Peptide availability and composition significantly impact L. lactis growth.
- Leucine and methionine are critical for L. lactis growth in milk-based environments.