Viability of NCTC 12900 in various concentrations of d- or l-lactate. d-Lactate was added to give final concentrations of 100 (◊), 150 (□), and 200 (○) mM. l-Lactate was added to give final concentrations of 50 (▴), 100 (⧫), 150 (▪), and 200 (•) mM. A dashed line represents the limit of detection (1.67 log10 CFU ml−1).