Fig 5.

Energetics of carbohydrate and Ca²⁺-citrate metabolism in Lb. casei. Lb. casei ATCC 334 was grown in mMRSGlc (A, D), mMRSGal (B, E), and mMRSCitCa (C, F). The cells were harvested at an OD₆₆₀ of 0.6 and loaded with BCECF for internal pH (pHin) measurements (A, B, and C) and incubated with the DiSC₃ fluorescent probe for measurement of the membrane potential (D, E, and F). For cytoplasmic pH measurements, 5 mM glucose, 5 mM galactose, or 2 mM citrate plus 2 mM Ca²⁺ was added at the time point indicated by the arrow. For membrane potential measurements, the cells were incubated with 2 mM Ca²⁺ to obtain a stable DiSC₃ fluorescent signal before glucose, galactose, and citrate were added (arrow) at the same concentrations. a.u., arbitrary units.