唾液酸和6′-唾液酸乳糖对仔猪肠道微生物体外发酵特性的影响

Effects of sialic acid and 6′-sialyllactose on in vitro fermentation characteristics of gut microbiota in weaned piglets

摘要:

6′-唾液酸乳糖(6′-sialyllactose, 6′-SL)是猪母乳寡糖中的重要组分，唾液酸(sialic acid, SIA)是唾液酸化乳寡糖的单体，它们均可调控人的结肠微生物结构。目前关于SIA和6′-SL在体外对仔猪结肠微生物的组成和发酵特性的影响鲜有报道。目的 探究SIA和6′-SL对哺乳仔猪结肠微生物组成及发酵特性的影响，为SIA和6′-SL调控哺乳仔猪肠道健康提供参考。方法 以3只哺乳仔猪的结肠混合食糜为微生物接种物，探究SIA和6′-SL对哺乳仔猪结肠微生物组成及发酵特性的影响。试验分为4组：无碳源(no carbon, NCB)、乳糖(lactose, LAC)、SIA和6′-SL，各组均为4个重复。结果 发酵至24 h时，6′-SL组的pH显著高于LAC组(P<0.05)；发酵至12 h和24 h时，SIA和6′-SL组的产气量均显著低于LAC组(P<0.05)；发酵至24 h时，SIA和6′-SL组的乙酸含量均显著高于LAC组(P<0.05)，丙酸和丁酸含量均显著低于LAC组(P<0.05)，显著提高了Chao1指数和ACE指数(P<0.05)；LAC组、SIA组和6′-SL组菌群的β多样性发生显著改变(P<0.05)；随着发酵时间延长，与LAC组相比，SIA组显著提高了芽孢杆菌门(Bacillota)、厌氧弧菌属(Anaerovibrio)和普氏栖粪杆菌属(Faecalibacterium)的相对丰度，降低了假单胞菌门(Pseudomonadota)、埃希氏菌-志贺氏菌(Escherichia-Shigella)、光冈菌属(Mitsuokella)和链球菌属(Streptococcus)的相对丰度(P<0.05)；6′-SL组显著提高了拟杆菌门(Bacteroidetes)普雷沃氏菌属Prevotella、拟杆菌属Bacteroides和罗氏菌属Roseburia，降低了假单胞菌门、芽孢杆菌门、巨单胞菌属(Megamonas)、埃希氏菌-志贺氏菌、光冈菌属和普雷沃氏菌科NK3B31组(Prevotellaceae_NK3B31_group)的相对丰度(P<0.05)。结论 6′-SL和SIA均可有效调控仔猪肠道菌群结构，6′-SL能提高拟杆菌门以及普雷沃氏菌属和拟杆菌属的相对丰度，而SIA能提高芽孢杆菌门以及厌氧弧菌属的相对丰度，且2种底物都明显促进仔猪结肠微生物发酵，提高短链脂肪酸(short chain fatty acids, SCFAs)产量，尤其是乙酸。

Abstract:

6′-sialyllactose (6′-SL) is an important component of porcine breast milk oligosaccharides, and sialic acid (SIA) is the monomer of sialylated breast milk oligosaccharides. Both can regulate the structure of human colonic microbiota. However, there are few reports regarding the effects of SIA and 6′-SL on the composition and fermentation characteristics of piglet colonic microbiota in vitro.Objective To investigate the effects of SIA and 6′-SL on the composition and fermentation characteristics of colonic microbiota in suckling piglets, aiming to provide a reference for using these substances to regulate gut health in piglets.Methods We used mixed colonic chyme from three suckling piglets as the microbial inoculum. The experiment was conducted with four groups: no carbon (NCB), lactose (LAC), SIA, and 6′-SL, each with four replicates.Results After 24 h of fermentation, the pH in the 6′-SL group was higher than that in the LAC group (P<0.05). After fermentation for 12 h and 24 h, the gas production in the SIA and 6′-SL groups was lower than that in the LAC group (P<0.05). At the time point of 24 h, the SIA and 6′-SL groups had higher acetic acid content and lower propionic acid and butyric acid content than the LAC group (P<0.05). Moreover, the SIA and 6′-SL groups had higher Chao1 and ACE indices than the LAC group (P<0.05). Beta diversity of the microbial community in the LAC, SIA, and 6′-SL groups changed (P<0.05). As fermentation progressed, compared with LAC, SIA increased the relative abundance of Bacillota, Anaerovibrio, and Faecalibacterium and decreased that of Pseudomonadota, Escherichia-Shigella, Mitsuokella, and Streptococcus (P<0.05); 6′-SL increased the relative abundance of Bacteroidetes, Prevotella, Bacteroides, and Roseburia and decreased that of Pseudomonadota, Bacillota, Megamonas, Escherichia-Shigella, Mitsuokella, and Prevotellaceae_NK3B31_group (P<0.05).Conclusion Both 6′-SL and SIA can effectively regulate the gut microbiota structure in piglets. Specifically, 6′-SL increases the relative abundance of Bacteroidetes, Prevotella, and Bacteroides, while SIA increases that of Bacillota and Anaerovibrio. Both substances promote colonic microbial fermentation in piglets to increase the production of short-chain fatty acids (SCFAs), especially acetic acid.