The concentration-dependent impact of cFDA/cFDA-SE in combination with PI on lag phase duration was also confirmed for L. lactis subsp. lactis S2 and L. lactis subsp. cremoris S3 (Table 1). In contrast to L. lactis subsp. lactis S2, growth in liquid media of the other two strains was entirely inhibited by double staining with 50 mM cFDA/cFDA-SE and 2 mM TOTO-1.