Meanwhile, for the tests on fermented dairy products, viability probe 5,6-cFDA (Invitrogen) replaced Syto 24 for the detection of the viable population in the products: 100 uL antibody labelled samples were incubated with 10 uL 5,6-cFDA (1 mM) in 1 mL PBS buffer in the dark at 37 C for 15 min prior to analysis.