壳聚糖螯合锌对大肠杆菌攻毒断奶大鼠回肠菌群结构及代谢产物的影响

Effects of chitosan-chelated zinc on ileal microbial community and metabolites in weaned rats challenged with Escherichia coli

本试验旨在研究日粮中添加壳聚糖螯合锌(chitosan-chelated zinc,CS-Zn)对大肠杆菌攻毒断奶大鼠回肠微生物及代谢产物的影响。试验选用24只断奶SD大鼠,随机分为对照组和试验组,对照组饲喂基础日粮,试验组饲喂基础日粮+640 mg/kg壳聚糖螯合锌(含锌50 mg/kg)。试验期为14 d,试验第10~12 d,所有大鼠每天灌胃总菌数为1010 CFU/只的大肠杆菌菌液,连续灌胃3 d。试验结束采集回肠食糜进行16S rRNA高通量测序分析结果显示,与对照组相比,试验组大鼠回肠微生物α多样性Shannon和Simposon指数显著降低(P<0.05);厚壁菌门相对丰度显著增加(P<0.05),拟杆菌门、变形菌门、放线菌门和疣微菌门的丰度显著降低(P<0.05);Romboutsia属和苏黎世杆菌属(Turicibacter)丰度显著增加(P<0.05),脱硫弧菌属(Desulfovibrio)和狭义梭菌属(Clostridium sensu stricto)丰度显著降低(P<0.05);同时,试验组丙酸、丁酸和乳酸的浓度显著上升(P<0.05)。研究表明,壳聚糖螯合锌主要通过上调有益菌的丰度,下调促炎菌脱硫弧菌属的丰度来调节肠道菌群结构,进而促进微生物代谢产物短链脂肪酸和乳酸的生成。

This study was to determine the effects of chitosan-chelated zinc(CS-Zn)supplementation on the ileal microbial community and metabolites in weaned rats challenged with Escherichia coli.A total of 24 weaned rats were randomly divided into a control group and a treatment group.The control group was fed with basic diet and the treatment group was fed with basic diet+640 mg/kg CS-Zn(containing 50 mg/kg zinc).The experimental period was 14 days,and on the 10th to 12th days,all the rats were given E.coli with a total bacteria count of 1010 CFU/day(dissolved in 4 mL of normal saline)by oral gavage every day for 3 consecutive days.At the end of the experiment,samples of ileum digesta were collected for 16 S rRNA high-throughput sequencing.The results showed that CS-Zn significantly reduced the Shannon and Simposon indexes of ileal microbialαdiversity(P<0.05).CS-Zn significantly increased the relative abundance of ileum Fimicutes(P<0.05),but reduced the relative abundance of Bacteroidetas,Proteobacteria,Actinbacteria,and Verrucomicrobia(P<0.05).CS-Zn significantly increased the abundance of Romboutsia and Turicibacter(P<0.05),but reduced the relative abundance of Desulfovibrio and Clostridium sensu stricto(P<0.05).Meanwhile,the concentrations of propionate,butyrate and lactic acid significantly increased in the treatment group(P<0.05).In summary,CS-Zn regulated intestinal microbiota by upregulating the abundance of beneficial bacteria and down-regulating the abundance of pro-inflammatory bacteria,and then improved the concentrations of short chain fatty acids and lactic acid in the animals.