摘要As a foodborne pathogen of global importance,Salmonella enterica serovar Enteritidis(S.Enteritidis)is a threat to public health that is mainly spread by poultry products.Intestinal Enterobacteriaceae can inhibit the colonization of S.Enteritidis and are regarded as a potential antibiotic substitute.We inves-tigated,in chicks,the anti-S.Enteritidis effects of Escherichia coli(E.coli)Nissle 1917,the most well-known probiotic member of Enterobacteriaceae.Eighty 1-d-old healthy female AA broilers were randomly divided into 4 groups,with 20 in each group,namely the negative control(group P),the E.coli Nissle 1917-treated group(group N),the S.Enteritidis-infected group(group S)and the E.coli Nissle 1917-treated and S.Enteritidis-infected group(group NS).From d 5 to 7,chicks in groups N and NS were orally gavaged once a day with E.coli Nissle 1917 and in groups P and S were administered the same volume of sterile PBS.At d 8,the chicks in groups S and NS were orally gavaged with S.Enteritidis and in groups P and N were administered the same volume of sterile PBS.Sampling was conducted 24 h after challenge.Results showed that gavage of E.coli Nissle 1917 reduced the spleen index,Salmonella loads,and inflammation(P＜0.05).It improved intestinal morphology and intestinal barrier function(P＜0.05).5.Enteritidis infection significantly reduced mRNA expression of angiotensin-converting enzyme 2(ACE2)and solute carrier family 6-member 19(SLC6A19)in the cecum and the content of Gly,Ser,Gln,and Trp in the serum(P＜0.05).Pretreatment with E.coli Nissle 1917 yielded mRNA expression of ACE2 and SLC6A19 in the cecum and levels of Gly,Ser,Gln,and Trp in the serum similar to that of uninfected chicks(P＜0.05).Additionally,E.coli Nissle 1917 altered cecum microbiota composition and enriched the abundance of E.coli,Lactobacillales,and Lachnospiraceae.These findings reveal that the probiotic E.coli Nissle 1917 reduced 5.Enteritidis infection and shows enormous potential as an alternative to antibiotics.