Aeration and supplementation with heme and menaquinone affect survival to stresses and antioxidant capability of Lactobacillus casei strains

The strains Lactobacillus casei N87, N811, N2014 (isolated from infant faeces) and CI4368 (from cheese) were used to evaluate the effect of aeration and supplementation with heme and menaquinone (promoting respiration) on the antioxidant capability and on the survival to simulated gastrointestinal transit and oxidative stresses. The probiotic Lactobacillus rhamnosus GG and L. casei Shirota were used for comparative purposes. L. casei N87 and N811 showed potential respiratory traits (increases in biomass and pH, oxygen tolerance and consumption, and production of antioxidant enzymes), while L. rhamnosus GG and L. casei Shirota were unable to activate aerobic pathways. Contrarily to probiotic strains, the four L. casei have the capability to produce catalase in both anaerobic and aerobic conditions, contributing to the expression of highly H2O2-tolerant phenotypes. Oxygen and heme/menaquinone supplementation, generally, improved tolerance of oxidative stresses and degradation of free-radicals, but significantly impaired the survival to simulated gastric juice. This study highlighted the greater robustness of respiration-competent L. casei strains, compared to L. rhamnosus GG and L. casei Shirota. The capability to reduce H2O2 and free-radicals may be exploited in food (prevention of oxidation in fermented foods) and human health (removal of toxic compounds; potential implication in the reduction of gastrointestinal and degenerative diseases) applications.