D-Glucose/D-Galactose (solid lines) and GalGlc/GalGal (dashed lines) ratios (A); GalGlc/GalLac (solid lines) and GalGal/GalLac (dashed lines) ratios (B) during lactose conversion by <i>B. breve</i> β-gal I (close symbol) and β-gal II (open symbol).

<p>The reactions were performed at 30°C at an initial lactose concentration of 200 g L<sup>−1</sup> in sodium phosphate buffer (pH 6.5) and 1 mM MgCl<sub>2</sub> with 1.0 U<sub>Lac</sub> mL<sup>−1</sup> β-gal I or 2.5 U<sub>Lac</sub> mL<sup>−1</sup> β-gal II.</p>