Metabolism of Functional Oligosaccharides and Antagonism of Foodborne Pathogens by Resting Cells of Limosilactobacillus reuteri

Based on the metabolic activity and biotransformation capacity of the resting cells of Limosilactobacillus reuteri, its ability to metabolize functional oligosaccharides and antagonize foodborne pathogens was explored. A phylogenetic tree for L. reuteri was constructed based on its 16S rRNA gene sequence. The environmental tolerance of the resting cells of L. reuteri was analyzed by acid and bile salt tolerance, and antibiotic sensitivity assays. The effects of functional oligosaccharides on the metabolism, surface hydrophobicity, adhesion capacity and reuterin (a broad-spectrum antibacterial) production ability of L. reuteri were evaluated by using modified media. Then, the inhibitory effect of the resting cells of L. reuteri on the adhesion of Staphylococcus aureus to Caco-2 cells and its growth in skim milk was explored. Results showed that both L. reuteri strains tested could tolerate extreme acidic conditions and bile salts for more than 3 h and were susceptible to common antibiotics. All functional oligosaccharides tested except xylo-oligosaccharides could be metabolized by the resting cells, and its growth, surface hydrophobicity and adhesion capacity were improved significantly by raffinose (P < 0.05). Raffinose could promote the production of reuterin from L. reuteri HLRE13 by utilizing glycerol, attaining a concentration of (1.34 ± 0.03) g/L. Glycerol promoted the inhibitory effect of L. reuteri HLRE13 on a variety of foodborne pathogens significantly (P < 0.001), and inhibited the adhesion of S. aureus to Caco-2 cells by 41.67% through exclusion. Furthermore, glycerol could promote L. reuteri HLRE13 to reduce the number of S. aureus to 10³ CFU/mL during co-culture. This study will provide a scientific basis for the functional development of resting cells of L. reuteri and its synergistic efficacy with functional oligosaccharides.