| ?-lactalbumin is one of the biologically active proteins in breast milk.The active peptide produced after digestion has immunomodulatory,antiviral and blood pressure inhibiting activities.However,its regulation of gut microbiota has not been reported.At present,?-lactalbumin is widely used in the addition of infant formula.Therefore,it is of great significance to study?-lactalbumin for regulating the balance of infant`s gut microbiota,increasing the relative abundance of probiotics,and exploring the reasonable addition amount in infant formula.In the study,the effects of different concentrations of ?-lactalbumin digestive juice on probiotics and pathogenic bacteria were explored by simulating gastrointestinal digestion in vitro.Bifidobacterium BB12,Bifidobacterium Bi-07,Lactobacillus acidophilus,Lactobacillus rhamnosus,probiotic mixed,Escherichia coli,Klebsiella pneumoniae,Clostridium perfringens were selected respectively as research targets.The results showed that ?-lactalbumin digestive juice can promote Bifidobacterium BB12?Bifidobacterium Bi-07?Lactobacillus acidophilus?Lactobacillus rhamnosus,the optimal concentrations were 0.2 mg/m L,0.02 mg/m L,0.1 mg/m L,and 0.2 mg/m L,respectively.?-lactalbumin digestive juice can inhibit Escherichia coli,Klebsiella pneumoniae,Clostridium perfringens,the optimal concentrations were 1 mg/m L,0.2 mg/m L,0.5mg/m L,respectively.The ?-lactalbumin digestive juice 0.2 mg/m L increased the viable count of probiotics in the gut microbiota,but reduced the viable counts of Escherichia coli,Klebsiella pneumoniae,and Clostridium perfringens.Further,the effects of ?-lactalbumin on immunity and gut microbiota were investigated by a rat test.The results showed that different doses of ?-lactalbumin could significantly increase the thymus index and the percentage of CD3~+ in peripheral blood(p <0.05).the medium and high doses could significantly increase the percentage of CD4~+ and CD4~+/CD8~+,serum IL-10 levels(p<0.05);the medium dose can significantly increase the content of IL-4,Ig G and Ig M in the serum of rats(p <0.05);the low dose can effectively increase the content of Ig A and Ig G in serum(p<0.05).Alpha diversity analysis showed that different doses of ?-lactalbumin had no significant effect on the diversity of rat gut microbiota at 14 days.Alpha diversity analysis showed that high dose and medium dose of ?-lactalbumin at the 28 th day of the experiment improved the diversity of the gut microbiota while taking into account the uniformity.Beta diversity analysis showed that each dose group was significantly different from the test group at 28 th days,and ?-lactalbumin had an effect on community structure.Species composition analysis showed that at the level of the Phylum,the gut microbiota of rats was dominated by Firmicutes and Bacteroidetes.Different doses of ?-lactalbumin were similar to those of breast milk.At the genus level,medium and lowdoses of ?-lactalbumin can increase the relative abundance of Lactobacillus,Blautia,and Akkermansia;All dose group can reduce the relative abundance of Prevotellaceae and Bacteroides,and the effect increases with decreasing concentration;All dose group can increase the relative abundance of Eubacterium xylanophilum group and maintain constant of Ruminococcaceae,Lachnospiraceae,and Clostridium sensu stricto-1.In summary,?-lactalbumin may release bioactive peptides during digestion to regulate the development of gut microbiota in infants.The latter metabolites mediate fluid immunity,ultimately affecting disease and health.100 mg/kg·BW is a suitable dose to adjust the gut microbiota.The results of this experiment can provide theoretical support for the addition of?-lactalbumin in infant formula,and lay a foundation for the scientific and healthy feeding of infants,and provide support for the healthy growth and development of infants in China. |
PDF Full Text Request