Dietary Supplementation Of ε-polylysine On Gut Microbiota And Nutrient Metabolism In Pigs And C57 Mice

ε-Polylysine,as a natural bacteriostatic agent,has attracted our attention.From the perspective of nutrient metabolism,we investigated the effects of different levels of ε-polylysine on gut microbiota and nutrient metabolism in C57 mice,which to explore the potential value of ε-polylysine on the digestion and metabolism of nutrients.The main results of this paper were as follows:Part 1 Effects of dietary supplementation of ε-polylysine on ileal microbiota structure and function in Ningxiang PigsWe chose 5 Ningxiang pigs(76.5 ± 5.26 kg)that were complete recovery healthy after fistula operation.We investigated how dietary supplementation with different ε-polylysine concentrations(0,20,40,80,and 160 ppm)affected the ileal microbiota in Ningxiang pigs using a replicated 5 × 5 Latin square method.Each experimental period included 10 days for diet adaptation.We collected feces and digesta samples.The results showed that: 1)ε-Polylysine significantly affected the digestibility of crude protein and crude fiber,as well as the utilization of metabolizable energy(P < 0.05).2)The relative abundances of 19 bacterial genera significantly increased,while those of 26 genera significantly decreased(P < 0.05).3)ε-Polylysine enhanced functional maturation,including changes in the metabolism of carbohydrates,amino acids,lipid,cofactors and vitamins by PICRUSt analysis.Part 2 ε-Polylysine affected the growth performance,intestine morphology and gut microbiota composition in C57 mice.In this experiment,we chose 80 3-week-old SPF male healthy C57 BL/6j mice,weighing 9.35 ± 1.13 g,which were randomly divided into 4 groups,4 replicates in each group and 5 C57 mice in each replicate.Each group was fed the same basal diet(AIN-76A)supplemented with 0 mg/kg,300 mg/kg,600 mg/kg,and 1200 mg/kg of ε-polylysine,respectively.Body weights were measured at the beginning of the experimental period,and then once per week.Fecal samples(n=12 each group)were collected at weeks four,six,and ten.At the end of the experiment(10 weeks),the mice were anesthetized and sacrificed,and intestine,liver and plasma samples(n=20 each group)were harvested.We compared the changes in growth performance and intestinal tissue morphology of C57 mice in the control and ε-polylysine groups(300,600 and 1200 mg/kg),and analyzed gut microbiota at three time points during the growth phase.The results were: 1)During the growth period of C57 mice,ε-polylysine reduced the body weight,and 1200 mg/kg ε-polylysine supplement in the dietary could lead mild damage on the intestinal epithelial cells.2)From4-week-old to 10-week-old,the richness of gut microbiota was richer with the increasing age.ε-Polylysine regulated the nutrient metabolism(including lipid metabolism,carbohydrate metabolism,energy metabolism and amino acid metabolism,etc.)by PICRUSt analysis.Part 3 The effects of ε-polylysine on plasma and liver metabolites profiling in C57 miceWe explored the changes in the liver and plasma metabolites profiling through the LCMS metabolomic analysis.Spearman’s rank correlation coefficient analysis was performed to examine the possible connection between the composition of intestinal microflora at the genus level and plasma metabolites in C57 mice.The results of the analysis were: 1)ε-Polylysine significantly reduced the levels of glycerophospholipid metabolites including phosphatidylcholine(PC),phosphatidylethanolamine(PE),lysophosphatidylcholine(lyso PC),and lysophosphatidylethanolamine(lyso PE)(P < 0.05),but had no effect on the PC/PE ratio(P > 0.05).2)Through Spearman’s analysis,the changes in abundance of genra Alistipes,Lachnospiraceae UCG-001 and Streptomyces were positively associated with PC,PE,lyso-PC,lyso-PE,1-Arachidonoylglycerophosphoinositol and OHOHA-PS.However,the abundance changes of the genera Blautia,Christensenellaceae R-7 group,Odoribacter,Allobaculum,Ruminococcaceae UCG-004,Ruminococcaceae UCG-005 and Lachnospiracea UCG-010 were negatively correlated with above glycerophospholipid metabolites.Part 4 Dietary ε-polylysine regulated the fat digestion and absorption pathway and glycerophospholipid metabolism pathwayWe explored the regulatory effect of ε-polylysine on fat digestion and absorption pathway and glycerophospholipid metabolic pathways in C57 mice through combined data analysis of DIA proteomics and metabolomics.The results showed that: 1)ε-Polylysine regulated the fat digestion and absorption in the small intestine,significantly reduced the expression of CD36 and SR-B1(P < 0.05),and significantly reduced the level of diacylglycerols in glycerolipid metabolism pathway(P < 0.05).ε-Polylysine promoted the process of phospholipid and cholesterol entering the blood by increasing ABCA1 level.2)ε-Polylysine significantly increased the activities of phospholipase D and choline phosphate/ethanolamine phosphotransferase(P < 0.05),but significantly reduced the activity of lysophosphatidylcholine acyltransferase(P < 0.05).In conclusion,ε-polylysine affected the nutrient digestibility and utilization of metabolizable energy in Ningxiang pigs by regulating intestinal microbiota.ε-Polylysine modulated the gut microbiota structure in C57 mice and altered liver and plasma metabolic profiles.It regulated fat digestion and absorption pathway and glycerophospholipid metabolism pathway in the small intestine as well.