Enzymatically prepared neoagaro-oligosaccharide improves broiler chicken growth performance and gut health by promoting the production of spermidine by Faecalibacterium

Neoagaro-oligosaccharide has tremendous prebiotic potentials for animals health, but the relevant mechanisms are unclear. Herein, we cloned and expressed marine bacterial agarase in Pichia pastoris GS115 and evaluated the role of the enzymatically prepared NAOS in improving chicken health. We found that dietary NAOS promoted chicken growth and improved the intestinal morphology and barrier function, and promoted gut digestion and absorption function. Metagenomic analysis indicated that NAOS modulated the chicken gut microbiota structure, function, and microbial interactions and especially promoted the growth of spermidine producing bacteria. Importantly, we demonstrated that NAOS can be utilized by Faecalibacterium prausnitzii to grow and to produce spermidine, which potentially regulates activates host autophagy, which in turn regulates biological processes and immunity function. Collectively, these results suggest that NAOS enhances growth performance and gut health by promoting the production of spermidine by Faecalibacterium.