INS and infection: PICRUSt analysis exhibited that functions related to microbial infection and anti-infection such as Salmonella infection, Shigellosis, nucleotide oligomerization domain-like (NOD-like) receptor signaling pathway, streptomycin biosynthesis, prodigiosin biosynthesis, acarbose and validamycin biosynthesis, biotin metabolism, ascorbate and aldarate metabolism, biosynthesis of vancomycin group antibiotics and insulin signaling pathway, were significantly enhanced in single SE-infected B group compared with the non-infected A group (P < 0.05) (Fig. 6a).