Lactobacilli prevent hydroxy radical production and inhibit Escherichia coli and Enterococcus growth in system mimicking colon fermentation

Abstract

Aims: To explore the effect of Lactobacillus on redox state of colon chyme.

Methods and results: Nine Lactobacillus strains were studied for the inhibition of lipid peroxide formation in Fe(2+)/ascorbate system and for their ability to chelate 'free' ferrous ion. The result shows both properties were strain specific and no relationship between them was found. Both properties of Lactobacillus paracasei Fn032, Lactobacillus rhamnosus GG (LGG) and Lactobacillus sp. Fn001 were successively decreasing. LGG and Fn032 significantly decreased hydroxyl radicals (P < 0.01) in colonic fermentation model, in which considerable hydroxyl radicals occurred spontaneously. Addition of ferrous ion induced the production of hydroxyl radicals, which could be significantly inhibited by LGG, Fn032 (P < 0.01) and Fn001 (P < 0.05). Ferrous ion significantly induced the growth of Enterococcus and Escherichia coli, which could be inhibited by all three Lactobacillus strains. Escherichia coli and Enterococcus show significantly positive correlation with hydroxyl radicals with R of 0.96 (P = 0.0002) and 0.91 (P = 0.0017), respectively.

Conclusions: Antioxidative Lactobacillus could modulate redox state in colonic fermentation system, which is related to their free radical-scavenging ability or antibacterial effect.

Significance and impact of the study: This study proves that Lactobacillus strain could influence the redox state of gut chyme. Evaluation of antioxidative ability might be a powerful method for screening probiotic Lactobacillus strains.