Dietary Tryptophan Modulate the Composition of the Ileum and Cecum microbiota in Weaned Piglets after Lipopolysaccharide Challenge

Abstract Background: The gut microbiota plays a critical role in metabolism and growth of piglets, and was modifiable by dietary tryptophan (Trp) in previous study. However, no studies focused on the investigation of whether additional dietary Trp supplementation would modulate the composition of ileum and cecum microbiota of piglets challenged by lipopolysaccharide (LPS). We conducted to investigate whether dietary tryptophan could alleviate dysbacteriosis of piglets after challenged with LPS.Methods: A total of 40 28 days old male weaning piglets were randomly allotted to five groups, include Con group (basal diet), LPS group (basal diet), 0.2% Trp group (0.2% Trp diet), LPS+0.2% Trp group (0.2% Trp diet) and LPS+0.4% group (0.4% Trp diet). On day 10, 20 and 29, Con and 0.2% Trp groups were injected with saline, LPS, LPS+0.2% Trp and LPS+0.4% Trp groups were injected with LPS respectively. The experiment lasted for 30 days.Results: These results showed that the major three phyla in ileum were Firmicutes, Proteobacteria and Actinobacteria, in cecum were Firmicutes, Bacteroidetes and Proteobacteria. Dietary with 0.2% Trp could attenuate the effect of LPS on the alpha diversity (diversity and richness) in ileum (P＜0.05). The alpha diversity of cecum microbiota was not affected by LPS or Try. The relative abundance of Turicibacte (P＜0.05) and unclassified_f__Peptostreptococccaceae (P＜0.05) were decreased but Lactobacillu (P＜0.05) was increased in ileum by LPS. Compared with LPS group, the relative abundance of Actinobacillus (P=0.07) was decreased in LPS+0.2% Trp group, and the level of Blautia (P=0.08) was increased in LPS+0.4% Trp group. The complexity of ileum microbiota was decreased by LPS. But the complexity of ileum microbiota was increased in LPS+0.2% and LPS+0.4% groups. The relative abundance of Lactobacillu was negative correlation with the majority of genus in ileum and positive correlation with the antioxidant ability of liver (P＜0.05). Conclusions: These finding indicated that Trp could alleviate dysbacteriosis induced by LPS, and ileum microbiota might have a self-protective mechanism to resist the injury induced by LPS through enriching Lactobacillu.