Production of Reuterin by Lactobacillus reuteri and Its Antimicrobial Activity in Fermented Milk Products

This study investigates the production of reuterin by Lactobacillus reuteri ATCC 53608, both in vitro and in situ in fermented milk products, and evaluates its antimicrobial activity against various microorganisms. Reuterin was synthesized in aqueous glycerol solution and within fermented milk, then tested against starter cultures (Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus), spoilage organisms (Penicillium expansum), pathogenic bacteria (Staphylococcus aureus, Salmonella enterica subsp. enterica, Listeria monocytogenes), and a surrogate pathogen (Escherichia coli DH5α). The results demonstrate that reuterin remains stable during refrigerated storage. Gram-positive bacteria were more resistant to reuterin than Gram-negative bacteria, with E. coli DH5α being the most sensitive (MIC 0.9 mM), while P. expansum and L. reuteri ATCC 53608 tolerated concentrations up to 10 mM and 8.5 mM, respectively. The presence of reuterin did not significantly affect the quality parameters of the fermented milk product, including pH, acidity, soluble solids, and color.