Inulin as a commercial prebiotic could selectively promote the growth of beneficial gut microbes such as lactic acid bacteria (LAB). Whether LAB in rabbit gut possesses the capability to metabolize and utilize inulin is little known. Therefore, this study recovered 94 LAB strains from neonate rabbits and found that only 29% (28/94) could metabolize inulin with both species- and strain-specificity. The most vigorous inulin-degrading strain, Lacticaseibacillus paracasei YT170, could efficiently utilize both short-chain and long-chain components through thin-layer chromatography analysis. From genomic analysis, a predicted fosRABCDXE operon encoding putative cell wall-anchored fructan β-fructosidase, five fructose-transporting proteins and a pts1BCA operon encoding putative β-fructofuranosidase and sucrose-specific IIBCA components were linked to long-chain and short-chain inulin utilization respectively. This study provides a mechanistic rationale for effect of inulin administration on rabbits and lays a foundation for synbiotic applications aimed at modulating the intestinal microbiota of young rabbits.

To investigate the capability, properties and molecular mechanism of inulin fermentation by lactic acid bacteria (LAB) from Sichuan pickle. Seventy-nine LAB strains were purified from thirty aged Sichuan pickle brine samples, and only twenty-one Lactiplantibacillus plantarum strains (26.58%, 21/79) derived from fifteen samples grew well through utilizing inulin as a carbon source. The fermentation tests through using long-chain inulin (lc-inulin) as a carbon source showed that only six L. plantarum strains grew well, while other fifteen strains could only utilize short-chain oligofructose (FOS), and thin-layer chromatography analysis evidenced a strain-specificity of inulin consumption patterns. L. plantarum YT041 is a vigorous inulin-fermenter, and whole genome sequencing data revealed that sacPTS1 and fosRABCDXE operons might be associated with the fermentation of FOS and lc-inulin respectively. The phenotype of inulin consumption is commonly present in LAB from Sichuan pickle, which is strain-specific and largely depends on their specific ecological niche and degree of polymerization.