The Truncated Gene cfaD′ Positively Regulates CFA/Ⅰ Expression of Enterotoxigenic Escherichia coli

The gene cluster cfaABCED’ of enterotoxigenic Escherichia coli, encoding the fimbriae which is called colonization factor antigen located on a plasmid. It is positively regulated by cfaR, a member of the AraC family, and the cfaD’ gene region, which is located downstream of cfaE and is homologous to cfaR, had been described as a truncated cryptic gene. In the present study we observed that the CFA/ fimbriae subunit, cfaB, was expressed in lower amount by the cfaABCED’ clone pNTP513 in host E. coli HB101. The expression of CFA/ diminished by deletion of cfaD’ gene region from pNTP513, and was restored by acquisition of cfaD’ in trans. Furthermore, CFA/ expression by cfaD’ deletion mutant, the cfaABCE clone, was remarkably increased by the presence of cfaD’ in trans in a topoisomerase A deficient strain of E. coli DM800. These data suggest that cfaD’ region is a functional region of gene, that regulates the CFA/ expression with cfaR by unknown mechanism.

Impact of an oligosaccharide-based polymer on the metabolic profiles and microbial ecology of weanling pigs experimentally infected with a pathogenic E.coli

Background Our previous study has reported that supplementation of oligosaccharide-based polymer enhances gut health and disease resistance of pigs infected with enterotoxigenic E.coli(ETEC)F18 in a manner similar to carbadox.The objective of this study was to investigate the impacts of oligosaccharide-based polymer or antibiotic on the host metabolic profiles and colon microbiota of weaned pigs experimentally infected with ETEC F18.Results Multivariate analysis highlighted the differences in the metabolic profiles of serum and colon digesta which were predominantly found between pigs supplemented with oligosaccharide-based polymer and antibiotic.The relative abundance of metabolic markers of immune responses and nutrient metabolisms,such as amino acids and carbohydrates,were significantly differentiated between the oligosaccharide-based polymer and antibiotic groups(q<0.2 and fold change>2.0).In addition,pigs in antibiotic had a reduced(P<0.05)relative abundance of Lachnospiraceae and Lactobacillaceae,whereas had greater(P<0.05)Clostridiaceae and Streptococcaceae in the colon digesta on d 11 post-inoculation(PI)compared with d 5 PI.Conclusions The impact of oligosaccharide-based polymer on the metabolic and microbial profiles of pigs is not fully understood,and further exploration is needed.However,current research suggest that various mechanisms are involved in the enhanced disease resistance and performance in ETEC-challenged pigs by supplementing this polymer.

Supplementation of oligosaccharide-based polymer enhanced growth and disease resistance of weaned pigs by modulating intestinal integrity and systemic immunity

Background:There is a great demand for antibiotic alternatives to maintain animal health and productivity.The objective of this experiment was to determine the efficacy of dietary supplementation of a blood group A6 type 1antigen oligosaccharides-based polymer(Coligo)on growth performance,diarrhea severity,intestinal health,and systemic immunity of weaned pigs experimentally infected with an enterotoxigenic Escherichia coli(ETEC),when compared with antibiotics.Results:Pigs in antibiotic carbadox or Coligo treatment groups had greater(P<0.05)body weight on d 5 or d 11post-inoculation(PI)than pigs in the control group,respectively.Supplementation of antibiotics or Coligo enhanced(P<0.05)feed efficiency from d 0 to 5 PI and reduced(P<0.05)frequency of diarrhea throughout the experiment,compared with pigs in the control group.Supplementation of antibiotics reduced(P<0.05)fecalβ-hemolytic coliforms on d 2,5,and 8 PI.Pigs in antibiotics or Coligo groups had reduced(P<0.05)neutrophil counts and serum haptoglobin concentration compared to pigs in the control group on d 2 and 5 PI.Pigs in Coligo had reduced(P<0.05)total coliforms in mesenteric lymph nodes on d 5 and 11 PI,whereas pigs in antibiotics or Coligo groups had reduced(P<0.05)total coliforms in spleen on d 11 PI compared with pigs in the control group.On d 5 PI,pigs in the Coligo group had greater(P<0.05)gene expression of ZO1 in jejunal mucosa,but less(P<0.05)m RNA expression of IL1B,IL6,and TNF in ileal mucosa,in comparison with pigs in the control group.Supplementation of antibiotics enhanced(P<0.05)the gene expression of OCLN in jejunal mucosa but decreased(P<0.05)IL1B and IL6 gene expression in ileal mucosa,compared with the control.On d 11 PI,supplementation of antibiotics or Coligo up-regulated(P<0.05)gene expression of CLDN1 in jejunal mucosa,but Coligo reduced(P<0.05)IL6 gene expression in ileal mucosa compared to pigs in the control group.Conclusions:Supplementation of Coligo improved growth performance,alleviated diarrhea severity,and enhanced gut health in weaned pigs infected with ETEC F18 in a manner similar to in-feed antibiotics.

体外发酵条件下嗜热链球菌S131对肠道健康的调控机制

该研究以HT-29细胞与人体肠道菌群批量发酵模拟系统相结合,探究嗜热链球菌S131对肠道屏障的影响、拮抗致病菌造成的肠道损伤及对有益菌的增殖效果。结果表明,与对照组相比S131使HT-29细胞黏蛋白MUC2、紧密连接蛋白ZO-1、ZO-2、Claudin-1与Occludin mRNA相对表达分别提升至1.34、4.59、2.17、5.81和4.25,同时能够缓解产肠毒素性大肠杆菌(Enterotoxigenic E.coli,ETEC)对相应基因表达的抑制,各基因分别提升至1.42、6.28、3.27、5.03和4.79。S131对ETEC造成的HT-29细胞炎症因子分泌增加具有显著抑制作用,使IL-8和IL-1β分别由821.79 pg/mL和2.22 pg/mL降至573.92 pg/mL和0.29 pg/mL。S131改善了ETEC造成的上皮细胞损伤,将细胞增殖率提升至21.07%。同时S131缓解了ETEC造成的AQP-3 mRNA相对表达下调,使AQP-3基因表达提升至1.21。并且通过qPCR检测发现S131提升了体外发酵体系中柔嫩梭菌属(Faecalibacterium)和多形拟杆菌属(Bacteroides thetaiotaomicron)的相对丰度,改善了ETEC造成的乳杆菌属(Lactobacillus)、双歧杆菌属(Bifidobacterium)、多形拟杆菌和柔嫩梭菌属的降低。综上,嗜热链球菌S131可能通过增强肠道屏障、拮抗致病菌损伤和调节肠道菌群来改善肠道健康。