Time course of GOS formation (A) and formation and degradation of GOS during lactose conversion (B) catalyzed by <i>B. breve</i> β-gal I (•) and β-gal II (○).

<p>The reaction was 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> using 1.5 U<sub>Lac</sub> mL<sup>−1</sup><sub>.</sub> Values are the mean of two independent experiments and the standard deviation was always less than 5%.</p>