甘露低聚糖对断奶仔猪肠道微生物体外发酵特性及菌群结构的影响

Effects of mannanoligosaccharides on in vitro fermentation characteristics and composition of intestinal microbiota in weaned piglets

摘要:

目的 采用微生物体外发酵技术，以低聚果糖(fructooligosaccharides, FOS)为对照，研究甘露低聚糖(mannanoligosaccharides, MOS)对断奶仔猪肠道微生物体外发酵特性及菌群结构的影响。方法 以仔猪空肠与结肠食糜微生物作为接种物，分别以FOS和MOS为底物，在0、6、12、24、48 h这5个时间点测定微生物产气量和发酵液pH，并收集每个时间点的发酵液用于后续微生物分析。结果 在体外空肠微生物发酵过程中，MOS组发酵液pH和产气量均显著高于FOS组(P<0.05)；发酵24 h时，与FOS相比MOS极显著提高了乙酸、丙酸及总短链脂肪酸(short-chain fatty acids, SCFAs)的含量(P<0.01)；MOS组甲酸产量极显著低于FOS组(P<0.01)；发酵48 h时MOS组乳酸含量极显著低于FOS组(P<0.01)。在体外结肠微生物发酵过程中，MOS组产气量显著高于FOS组(P<0.05)；发酵48 h时MOS组甲酸、乙酸、丁酸、总SCFAs和乳酸的产量均极显著高于FOS组(P<0.01)。空肠发酵液16S rRNA基因测序结果显示，发酵48 h时MOS组Shannon和Simpson指数均极显著高于FOS组(P<0.01)，且两组之间微生物菌群组成差异明显。此外，MOS组双歧杆菌属(Bifidobacterium)、黏液乳杆菌属(Limosilactobacillus)和巨球形菌属(Megasphaera)菌属的相对丰度显著高于FOS组(P<0.05)。结论 与FOS相比，仔猪小肠微生物群能够利用MOS显著改善微生物区系，提高Bifidobacterium等有益菌的丰度，增加产气量，促进乙酸等SCFAs的产生，提示MOS具有改善仔猪小肠微生态的潜力。

Abstract:

Objective To investigate the effects of mannanoligosaccharides (MOS) on the in vitro fermentation characteristics and composition of intestinal microbiota in weaned piglets by using an in vitro microbial fermentation technique, with fructooligosaccharides (FOS) taken as the control.Methods Using microbial inocula derived from the jejunal and colonic chyme of piglets, with FOS and MOS as respective substrates, this study measured microbial gas production and fermentation broth pH at five time points (0, 6, 12, 24, and 48 h), and collected fermentation broth samples at each time point for subsequent microbial analysis.Results In the in vitro jejunal microbial fermentation system, both the fermentation broth pH and gas production in the MOS group were significantly higher than those in the FOS group (P<0.05). At 24 h of fermentation, compared with FOS, MOS significantly increased the concentrations of acetate, propionate, and total short-chain fatty acids (SCFAs) (P<0.01). The formate production in the MOS group was significantly lower than that in the FOS group (P<0.01). At 48 h of fermentation, the lactate concentration in the MOS group was significantly lower than that in the FOS group (P<0.01). In the in vitro colonic microbial fermentation system, gas production in the MOS group was significantly higher than that in the FOS group (P<0.05). At 48 h of fermentation, the production of formate, acetate, butyrate, SCFAs, and lactate in the MOS group was significantly higher than that in the FOS group (P<0.01). The 16S rRNA gene sequencing results of the jejunal fermentation broth revealed that at 48 h of fermentation, both the Shannon and Simpson indices in the MOS group were significantly higher than those in the FOS group (P<0.01). Furthermore, the microbiota composition exhibited disparity between the MOS and FOS groups. Moreover, the relative abundances of Bifidobacterium, Limosilactobacillus, and Megasphaera were significantly higher in the MOS group than in the FOS group (P<0.05).Conclusion Compared to FOS, MOS enabled the microbiota in the small intestine of piglets to significantly improve the microbial community structure, increase the abundance of beneficial bacteria such as Bifidobacterium, enhance gas production, and promote the generation of acetate and other SCFAs. These findings suggested that MOS held potential for modulating microecology in the small intestine of weaned piglets.