Redox potential to discriminate among species of lactic acid bacteria

Abstract

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 acid bacteria. Methods and Results: Eighty‐eight strains belonging to 10 species of lactic acid bacteria (LAB) isolated from traditional Italian cheeses were studied for their reduction activity: Enterococcus faecalis, Enterococcus faecium, Enterococcus durans, Streptococcus thermophilus, Lactococcus lactis ssp. lactis, Lactobacillus paracasei ssp. paracasei, Lactobacillus plantarum, Lactobacillus delbrueckii ssp. bulgaricus, Lactobacillus helveticus and Pediococcus pentosaceus. It was observed that the lactococci reached minimum redox potential before the lactobacilli. The reduction rate of Enterococcus spp. and L. lactis ssp. lactis was higher than that of the streptococci and Lactobacillus spp. All the P. 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 the same species. Significance and Impact of the Study: The reduction aptitude of strains might be used to select and adapt appropriate strains for use as starters for dairy products.

Contribution of bacteria to redox potential (E h) measurements in sediments

“…This corroborates redox development described for other bacterial species (e.g. Brasca et al 2007;Reichart et al 2007;Tachon et al 2010). At the onset of the stationary growth phase, redox potential measurements became more variable.…”

“…The redox measurements were similar in both liquid cultures and mono-specific sediment microcosms, although sediment microcosm appeared more variable among replicates compared to liquid cultures. However, the reported variations correspond well with species-specific E h variations as described previously (Brasca et al 2007). Subsequent addition of formalin in order to stop bacterial metabolism at the progressive stage of bacterial growth reduced variability in E h measurements (Fig 1a-c, right panel).…”

“…Increasing evidence suggests that bacteria are capable of creating redox conditions which are visible as speciesspecific continuous E h measurements (Brasca et al 2007;Reichart et al 2007;Michelon et al 2010;Ignatova et al 2010;Tachon et al 2010). It has been demonstrated that continuous measurements of E h are valuable for tracking bacterial metabolic activities in liquid cultures (e.g.…”

Effects of varying proportions of concentrates on ruminal-reducing power and bacterial community structure in dry dairy cows fed hay-based diets

“…Some studies showed that it plays an important role in many biological media such as milk-based products (Brasca et al, 2007), wine (Tomlinson and Kilmartin, 1997) and the rumen (Marounek et al, 1982;Marden et al, 2008), where E h is a major factor determining the type of microorganisms that will grow in the milieu (Brasca et al, 2007). Because of the continuous fermentative processes in the rumen involving different simultaneous chemical reactions, it seems interesting to focus on E h in such a reducing environment.…”

Influence of cultivation conditions on the growth of Lactobacillus acidophilus, Bifidobacterium sp., and Streptococcus thermophiles, and on the production of organic acids in fermented milks

“…The reason was the interaction between the starter bacteria. Streptococci lowered the redox potential (Brasca et al 2007), which supported the growth of bifibobacteria (Bolbuc et al 2006) and lactobacilli. On the contrary, lactobacilli released amino acids from milk proteins (Lane & Fox 1996) which stimulated the growth of streptococci (Ashraf & Shah 2011) and bifidobacteria (Bolbuc et al 2006).…”