Glutamate uptake in Lactobacillus delbrueckii subsp. bulgaricus CNRZ 208 and its enhancement by a combination of Mn2+ and Mg2+

Abstract

Aims: To demonstrate the mechanism of glutamate uptake in the dairy strain Lactobacillus delbrueckii subsp. bulgaricus CNRZ 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 K t of 2AE8 lmol l )1 and a V max of 900 lmol s )1 (g dry weight) )1 . The activity was optimal at pH 7AE3 and 50°C, was independent of the glutamate charge, and was enhanced by Mn 2+ + Mg 2+ 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 Mn 2+ and Mg 2+. Conclusions:We demonstrated for the first time that an active transport system governs the uptake of the essential amino acid glutamate in Lact. delbrueckii subsp. bulgaricus CNRZ 208, the activity of which is enhanced by a combination of Mn 2+ and Mg 2+ . Significance and Impact of the Study: The potential of the findings is discussed with reference to the growth of Lact. delbrueckii subsp. bulgaricus in mixed-strain cultures for the dairy industry.

Modified chemically defined medium for enhanced respiratory growth ofLactobacillus caseiandLactobacillus plantarumgroups

“…; de Giori et al . ). In these species, contrarily to the branched‐chain amino acids which were transported by a secondary proton motive force‐dependent system, l ‐glutamate and l ‐aspartate (like glutamine, histidine, arginine and tyrosine) were moved by primary ATP‐driven carriers.…”

Contribution of glutamate decarboxylase in Lactobacillus reuteri to acid resistance and persistence in sourdough fermentation

“…Glutamine:GABA antiport by gadC or analogues has not been shown experimentally [22]. However, ATP-dependent glutamate transport enzymes in L. lactis and L. delbrueckii also transport glutamine with high affinity [42,43]. …”

Enzymatic Synthesis of High-Molecular-Mass Poly-γ-Glutamate and Regulation of Its Stereochemistry

“…Figure 4B shows that the activity of the inactivated PGA synthetic system was restored when the reaction mixture was supplemented with (20,23) but also to influence the stereochemical properties of the polymers produced (23,25). Several biological experiments have revealed that Mn 2ϩ is involved in the uptake of glutamate (10,11,16). The genome analysis of B. subtilis (35) proved that its chromosome carries an operon structure that includes the glr and ysmB genes (8).…”