Redox potential to discriminate among species of lactic acid bacteria

Aims: to verify to what degree reducing capacity is a characterizing parameter of a species, and of the strains themselves within a given species, of lactic bacteria. Methods and Results: 88 strains belonging to 10 species of lactic acid bacteria isolated from traditional Italian cheeses were studied for their reduction activity: Enterococcus faecalis, Enterococcus faecium, Enterococcus durans, Streptococcus thermophilus, Lactococcus lactis ss lactis, Lactobacillus paracasei ss paracasei, Lactobacillus plantarum, Lactobacillus delbrueckii ss bulgaricus, Lactobacillus helveticus and Pediococcus pentosaceus. It was observed that the lactococci reached minimum Eh before the lactobacilli. The reduction rate of Enterococcus spp. and L. lactis ss lactis was higher than that of the streptococci and Lactobacillus spp. All the Ped. pentosaceus strains had poor reduction activity compared with the other species. Conclusions: The evolution of the redox potential in milk over a time span of 24 h has been found to be a parameter that characterizes a species: the different courses corresponding to the species in question are clearly evident, and interesting differences can also be noted within