Ren Lulu, Cao Qingyun, Ye Hui, Dong Zemin, Zhang Changming, Yan Fei, Zhou Yuping, Zhou Huiyun, Zuo Jianjun, Wang Weiwei
Guangdong Provincial Key Laboratory of Animal Nutrition Control, College of Animal Science, South China Agricultural University, Guangzhou, 510642, China.
BMC Microbiol. 2025 Apr 22;25(1):227. doi: 10.1186/s12866-025-03948-y.
Avian pathogenic Escherichia coli (APEC) threatens both poultry production and human health. Xylooligosaccharides (XOS) may suppress pathogenic bacteria through prebiotic actions. However, the influences of single degree of polymerization (DP) on the inhibition of APEC by XOS remain unknown. This study aimed to probe if XOS and their major monomers (xylobiose, xylotriose and xylotetraose) could differentially combat APEC via prebiotic actions using an in vitro fermentation model with chicken cecal microbiota.
Microbiota were randomly divided into 7 groups (5 replicate tubes/group). Control group (CON) received no treatment; XOS group received commercial XOS mixtures; APEC group received APEC; XA, X2, X3 and X4 groups received APEC combined with commercial XOS mixtures, xylobiose, xylotriose and xylotetraose, respectively.
XOS and their major monomers mitigated APEC-induced decline (p < 0.05) in gut microbial α-diversity, with xylotetrose showing the least effect. Gut microbiota in XA, X2, X3 and X4 groups clustered together, with a relative separation observed in X4 group. XOS and their monomers elevated (p < 0.05) the abundances of Firmicutes, Bacteroidota and several probiotics (Lactobacillus, Bacteroides and Megamonas), but reduced (p < 0.05) the abundances of Proteobacteria and Escherichia-Shigella, with xylotetraose exhibiting the least efficacy. Besides, xylotriose and xylotetrose had an advantage over xylotetraose in promoting microbial production of short-chain fatty acids. Metabolomics analysis revealed that APEC challenge mainly downregulated (p < 0.05) several amino acids metabolism pathways of gut microbiota, while xylotriose had an inferiority to XOS in upregulating (p < 0.05) histidine metabolism pathway. Furthermore, microbial fermentation metabolites of all XOS monomers lowered (p < 0.05) certain virulence genes expression in APEC, with xylotriose being the most advantageous.
XOS and their major monomers differentially improved gut microbiota and metabolite profiles in chicken gut against APEC challenge. Overall, xylotriose exhibited the greatest inhibition against APEC abundance and virulence. Our findings underscore the role of single DP in influencing the prebiotic actions of XOS against APEC, providing a basis for the reasonable application of XOS in diets to combat bacterial challenge.
禽致病性大肠杆菌（APEC）对家禽生产和人类健康均构成威胁。低聚木糖（XOS）可能通过益生元作用抑制病原菌。然而，单聚合度（DP）对XOS抑制APEC的影响尚不清楚。本研究旨在利用鸡盲肠微生物群的体外发酵模型，探究XOS及其主要单体（木二糖、木三糖和木四糖）是否能通过益生元作用不同程度地对抗APEC。
将微生物群随机分为7组（每组5个重复管）。对照组（CON）不做处理；XOS组接受市售XOS混合物；APEC组接受APEC；XA、X2、X3和X4组分别接受APEC与市售XOS混合物、木二糖、木三糖和木四糖的组合。
XOS及其主要单体减轻了APEC诱导的肠道微生物α多样性下降（p < 0.05），木四糖的效果最差。XA、X2、X3和X4组的肠道微生物群聚集在一起，X4组有相对分离。XOS及其单体提高了（p < 0.05）厚壁菌门、拟杆菌门和几种益生菌（乳酸杆菌属、拟杆菌属和巨单胞菌属）的丰度，但降低了（p < 0.05）变形菌门和埃希氏菌-志贺氏菌属的丰度，木四糖的效果最差。此外，木三糖和木四糖在促进微生物产生短链脂肪酸方面优于木二糖。代谢组学分析表明，APEC攻击主要下调了（p < 0.05）肠道微生物群的几种氨基酸代谢途径，而木三糖在上调（p < 0.05）组氨酸代谢途径方面不如XOS。此外，所有XOS单体的微生物发酵代谢产物均降低了（p < 0.05）APEC中某些毒力基因的表达，木三糖最为有利。
XOS及其主要单体在鸡肠道中针对APEC攻击不同程度地改善了肠道微生物群和代谢物谱。总体而言，木三糖对APEC丰度和毒力的抑制作用最大。我们的研究结果强调了单DP在影响XOS对APEC益生元作用中的作用，为XOS在日粮中合理应用以对抗细菌攻击提供了依据。
