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Glutamate uptake in Lactobacillus delbrueckii subsp. bulgaricus CNRZ 208 and its enhancement by a combination of Mn 2+ and Mg 2+
Author(s) -
De Giori G. Savoy,
FoucaudScheunemann C.,
Ferchichi M.,
Hemme D.
Publication year - 2002
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1046/j.1472-765x.2002.01208.x
Subject(s) - lactobacillus delbrueckii subsp. bulgaricus , lactobacillus , glutamine , strain (injury) , lactobacillaceae , glutamate receptor , lactic acid , chemistry , biochemistry , bacteria , biology , amino acid , fermentation , genetics , receptor , anatomy
Aims:To demonstrate the mechanism of glutamate uptake in the dairy strainLactobacillus delbrueckiisubsp.bulgaricusCNRZ 208, and to characterize key aspects of the system.Methods and Results:Glutamate uptake proceeded via an active transport system requiring an exogenous source of energy. The system also transported aspartate and glutamine. It was unique, with a Ktof 2·8 µmol l−1and a Vmaxof 900 µmol s−1(g dry weight)−1. The activity was optimal at pH 7·3 and 50°C, was independent of the glutamate charge, and was enhanced by Mn2+ + Mg2+in combination. Inhibition of the activity by uncouplers and ionophores showed that transport was driven by an ATP‐dependent mechanism involving the proton‐motive force. This inhibition was partially abolished in the presence of both Mn2+and Mg2+ . Conclusions:We demonstrated for the first time that an active transport system governs the uptake of the essential amino acid glutamate inLact. delbrueckiisubsp.bulgaricusCNRZ 208, the activity of which is enhanced by a combination of Mn2+and Mg2+ . Significance and Impact of the Study:The potential of the findings is discussed with reference to the growth ofLact. delbrueckiisubsp.bulgaricus in mixed‐strain cultures for the dairy industry.