Lactobacillus paracasei metabolism of rice bran reveals metabolome associated with Salmonella Typhimurium growth reduction

AIMS This study aimed to determine the effect of a cell-free supernatant of Lactobacillus paracasei ATCC 27092 with and without rice bran extract (RBE) on Salmonella Typhimurium 14028s growth, and to identify a metabolite profile with antimicrobial functions. METHODS AND RESULTS Supernatant was collected from overnight cultures of L. paracasei incubated in the presence (LP+RBE) or absence (LP) of RBE and applied to S. Typhimurium. LP+RBE reduced 13·1% more S. Typhimurium growth than LP after 16 h (P < 0·05). Metabolite profiles of LP and LP+RBE were examined using nontargeted global metabolomics consisting of ultra-high-performance liquid chromatography coupled with tandem mass spectrometry. A comparison of LP and LP+RBE revealed 84 statistically significant metabolites (P < 0·05), where 20 were classified with antimicrobial functions. CONCLUSIONS LP+RBE reduced S. Typhimurium growth to a greater extent than LP, and the metabolite profile distinctions suggested that RBE favourably modulates the metabolism of L. paracasei. These findings warrant continued investigation of probiotic and RBE antimicrobial activities across microenvironments and matrices where S. Typhimurium exposure is problematic. SIGNIFICANCE AND IMPACT OF THE STUDY This study showed a novel metabolite profile of probiotic L. paracasei and prebiotic rice bran that increased antimicrobial activity against S. Typhimurium.