Decrease of <Emphasis Type="Italic">N</Emphasis>-nitrosodimethylamine and <Emphasis Type="Italic">N</Emphasis>-nitrosodiethylamine by <Emphasis Type="Italic">Lactobacillus pentosus</Emphasis> R3 is associated with surface-layer proteins

The objective of this study was to evaluate the ability of five strains of meat-borne bacteria to decrease N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) and to elucidate the mechanism in Mann-Rogosa-Sharp (MRS) broth. Lactobacillus pentosus R3 was found to be the most effective in decreasing the concentration of the two N-nitrosamines (NAs) in MRS broth, with a rate of 22.05% for NDMA and 23.31% for NDEA. The concentration of the two NAs could not be reduced by either extracellular metabolites or intracellular extracts of Lb. pentosus R3 (P?>?0.05), and proteinaceous substances in the cell debris were found to be responsible for the decrease. These were surface-layer proteins (SLPs) located on the cell wall. Therefore, the decrease in NDMA and NDEA by Lb. pentosus R3 is associated with its SLPs. Lb. pentosus R3 may be developed as a starter culture in the production of fermented foods with lower NAs.