Fig 1.
The distribution of eliminating activities for cumene and linoleic hydroperoxide in lactic acid bacteria and the difference in their capacities.
(A) Twenty lactic acid bacterial strains and typical bacterial species were cultured under specific conditions described in the Materials and Methods section. Each living cell was exposed to various concentrations of cumene hydroperoxide at 0.3, 1.0, and 3.0 mM for 1.5 h. After treatment, the extent of decomposition of the hydroperoxide, as their eliminating activity, was determined by calculating the difference between the initial concentration and the remaining concentration in the culture medium. The bar graph represents the mean values from three independent experiments, and error bars indicate the standard deviation (SD). (B) The same twenty lactic acid bacterial strains and typical bacterial species as (A) were cultured under specific conditions described in the Materials and Methods section. Each living cell was exposed to various concentrations of linoleic acid hydroperoxide at 0.25, 0.5, and 1.0 mM for 1.5 h at 37°C. After treatment, the extent of decomposition of the hydroperoxide was calculated as in (A).
Table 1.
Isolation of lactic acid bacteria exhibiting high eliminating activity for environmental hydrogen peroxides from fermented foods.
Fig 2.
Relationship between the eliminating activity and survival rate of lactic acid bacteria in the presence of cumene or linoleic acid hydroperoxide.
(A) Bacterial cells were incubated with various concentrations of cumene hydroperoxide from 0.3 to 3 mM for 1.5 h. After treatment, the cells were diluted and plated, and then the developed colonies were defined as living cells. The eliminating activity for substrate was estimated as described in Fig 1. The relationship between the number of living cells (lines) and the eliminating activity for hydroperoxide (bars) was plotted for each case. The data are mean values of three independent experiments. (a) L. plantarum NRIC 1067T and L. plantarum P1-2 strain (b) E. coli NRIC1518, P. pentosaceus NRIC 0099T, and P. pentosaceus Be1 strain (c) L. acidophilus NRIC 1547T, S. thermophilus NRIC 0256T and B. subtilis NRIC 1015. (B) The same bacterial cells as (A) were incubated with various concentrations of linoleic acid hydroperoxide from 0.25 to 1 mM for 1.5 h at 37°C. After treatment, the cells were diluted and plated, and then the developed colonies were defined as living cells. The eliminating activity for substrate was estimated as described in (A). (a) L. plantarum NRIC 1067T and L. plantarum P1-2 strain (b) E. coli NRIC1518, P. pentosaceus NRIC 0099T, and P. pentosaceus Be1 strain, (c) L. acidophilus NRIC 1547T, S. thermophilus NRIC 0256T, and B. subtilis NRIC 1015.
Fig 3.
Lactobacillus plantarum P1-2 reduces cumene and linoleic acid hydroperoxide to the corresponding hydroxyls.
(A) L. plantarum P1-2 was aerobically cultured in GYP medium, and the cells were incubated in 50 mM sodium phosphate (pH 7) containing 25 mM glucose and 3 mM cumene hydroperoxide for 1.5 h at 37°C. After the reaction, each metabolite was analyzed by HPLC equipped with an ODS column. Cumene hydroperoxide and the corresponding alcohol (2-phenyl-2-propanol) were eluted at retention times of 19 and 13 min, respectively. (B) L. plantarum P1-2 was aerobically cultured in GYP medium, and the cells were incubated in 50 mM sodium phosphate (pH 7) containing 25 mM glucose, and 100 μM 13-HpODE for 3 h at 37°C. 13-HpODE was used as the substrate of linoleic acid hydroperoxide. 100 μM 13-HpODE could be dissolved in this system without Triton X-100. After the reaction, each metabolite was analyzed by HPLC equipped with an ODS column. 13-HpODE and the corresponding hydroxyl (13-HODE) were eluted with retention times at 60.5 and 49.0 min, respectively.
Fig 4.
Prolongation of the lifespan of C. elegans Δfer-15;mev-1 with lactic acid bacteria.
E. coli OP50 (gray), S. thermophiles NRIC0256T (green), L. plantarum P1-2 (red), and P. pentosaceus Be1 (blue) were administered to C. elegans Δfer-15;mev-1 at the growth stage L4. The mutants were hatched on pH stat GYP medium, and their lifespan was monitored until annihilation. Statistical analysis was performed using Student’s t-test and Tukey’s multiple-range test. The least significant difference test was used for means separation at P < 0.05 within each strain. One hundred animals were measured for each strain at 25°C.
Fig 5.
Lipid peroxidation levels of plasma and tissues obtained from iron-overloaded rats.
Lipid peroxidation in rats was induced by 0.5% iron fumarate (Fe), and the MDA level was measured in each organ. Data are expressed as the mean values ± SD (n = 9). An asterisk (*) indicates a statistical difference of P < 0.05.
Fig 6.
The effect of Lactobacillus plantarum P1-2 administration on the liver and colonic mucosa of iron-overloaded rats, using a colonic mucosal lipid peroxidation model.
L. plantarum P1-2 was administered to iron-overloaded rats, and the MDA levels in the liver and colonic mucosa were compared to those of the healthy (control) and iron-overloaded rats (Fe). S. thermophilus NRIC0256T was also tested as a control strain. The data are the mean values ± SD (n = 6), and the different letters indicate the statistical significance at P < 0.05.