Some Factors Which Affect Amino Acid Uptake by Saccharomyces carlsbergensis

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RESUMO

When fully grown cells of Saccharomyces carlsbergensis were suspended in a solution of glucose and labeled amino acids, there was a lag phase before rapid uptake of certain amino acids. During this lag, significant amounts of sugar were utilized. The lag phase varied in length, depending upon the amino acid under study, but could be shortened by aeration of the cells and eliminated by their preincubation in glucose solution. Divalent metal ions, especially Ca2+ added during the early stages of the lag phase, increased the length of the lag, an effect that could be reversed by washing with ethylenediaminetetraacetate, but amino acids which normally showed little or no lag before uptake were insensitive to Ca2+. The rate of uptake of amino acids or of sugar was essentially unaffected by Ca2+, whereas 2,4-dinitrophenol caused an overall decrease in the rate of uptake of all amino acids tested. The relevance of these observations to commercial brewing practice is shown.

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