(A) The intracellular ATP concentration presented as light emission, in S. thermophilus A16-945 (urease-negative) EdC in mixed cultures. The A16-945 EdC were mixed with the wild-type EdC at the following ratios (v/v): 100% A16-945 (white triangles), 95% A16-945 (grey circles), 90% A16-945 (yellow circles), 80% A16-945 (red circles), and 50% A16-945 (black circles). The EdC were activated with 14 mM lactose/0.5 mM urea. (B) The intracellular ATP concentration, presented as light emission, in Lactococcus lactis 1403-945 (urease-negative) EdC in mixed cultures. The urease-negative EdC were mixed with the wild-type EdC at a 1∶1 ratio. The mixed EdC cultures were acitvated with 0.5 mM urea (white squares), 14 mM lactose (green squares) or 14 mM lactose/0.5 mM urea (red squares). The error bars represent the SEM.