Lactobacillus delbrueckii subsp lactis strain CIDCA 133 inhibits nitrate reductase activity of Escherichia coli

HUGO, A. A.; DE ANTONI G.L Y PÉREZ P.F.

INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY

Elsevier

Año: 2006 vol. 111 p. 191 - 196

0168-1605

The aim of the present work was to investigate the effect of strain CIDCA 133 on the nitrate reductase activity of a non-pathogenic Escherichia coli strain. Suspensions containing different ratios of the strains under study were coincubated in MRS or MRS without glucose. The nitrate reductase activity was determined by using a diazotization reaction for nitrite. Presence of live lactobacilli leads to a dose-response diminution in the specific nitrate reductase of Escherichia coli even when no acidification occurred. Killing of lactobacilli by UV treatment completely abolished the anti nitrate reductase effect. In addition, chloramphenicol (100 µg/ml) significantly abrogated the effect that in turns was only partially observed with filtered spent culture supernatants of lactobacilli.  Lactobacillus delbrueckii subsp lactis strain CIDCA 133 is able to antagonize the nitrate reductase activity of Escherichia coli. This effect is not due to a diminution of the viability nor is depending on the acidification of the medium. Viability and protein synthesis are needed for maximal anti nitrate reductase activity. Modulation of the enzymatic activity of intestinal microorganisms by means of selected microorganisms constitutes a further insight on the mechanisms by which probiotics lead to beneficial effects. Administration of probiotic strains able to modulate microbial intestinal activities could leads to a protection of the host against harmful effects of some members of the intestinal microflora.