The uptake of amino acids and peptides byStreptococcus lactis

Summary Peptide and amino acid transport inStreptococcus lactiswas both energy-and temperature-dependent. Separate systems were present for the transport of amino acids, dipeptides and oligopeptides as well as for individual amino acids. Both tri- and tetra-peptides were readily transported while an apparent size restriction at the point of uptake resulted in a relatively low rate of uptake of the pentapeptide. The effects of pH, temperature and salt concentration on the uptake of amino acids and peptides were studied. Exchange reactions played a significant role in the uptake of both peptides and amino acids.