Metabolism of Prebiotic Oligosaccharides by Lactic Acid Bacteria Isolated From Rabbits: Insights into Strain-Specific Utilization and Applications

To investigate the in vitro utilization of functional oligosaccharides by lactic acid bacteria (LAB) isolated from rabbits, characterize their metabolic kinetics and genomic determinants, and evaluate their in vitro probiotic traits when grown on oligosaccharides. A total of 92 LAB strains from weaned rabbits were screened for utilization of isomaltose- (IMO), galactose- (GOS), chitosan- (COS), and mannose-oligosaccharides (MOS). Strain- and substrate-specific utilization patterns were observed: 63% utilized IMO, 68.5% GOS, 16.3% MOS, and none metabolized COS. Lacticaseibacillus paracasei YT170-selected for its broad substrate range-showed distinct growth kinetics and pH dynamics on IMO, GOS, and MOS. Genomic analysis revealed specialized carbohydrate-active enzymes (CAZymes) for each oligosaccharide. After 72 h fermentation by YT170, cell-free supernatants from three oligosaccharides exhibited enhanced antioxidant activities (DPPH scavenging >88%) and substrate-dependent antimicrobial effects: MOS fermentation most effectively inhibited Escherichia coli (ZOI: 21.30 ± 0.66 mm vs. LGG 19.33 ± 0.29 mm), while GOS fermentation showed maximal activity against Staphylococcus aureus (ZOI: 25.17 ± 0.95 mm). Oligosaccharide utilization by LAB from rabbits is strain- and substrate-specific, and L. paracasei YT170 demonstrates metabolic versatility, enabling synbiotic design with IMO, GOS, or MOS to modulate gut microbiota in weaned rabbits, but further in vivo studies are required.