Bacteriostasis Of Quercetin In Vivo And In Vitro

240 of 39-week-old laying hens were randomly divided into four treatment groups consisting of 6 replicates of 10 laying hens in one-factor design, respectively. The laying hens were given either a basal diet or a basal diet supplemented with 0.02%, 0.04% and 0.06% quercetin. The experiment lasted for 8 weeks. E. Coli, Salmonella, Pasteurella, E. faecalis, Staphylococcus aureus, Proteusbacillus vulgaris, Pseudomonas aeruginosa, Enterococcus were tested strains in vitro using Oxford cup method. This study was aimed at investigating the bacteriostasis of quercetin on infectious bacteria in poultry in vivo and in vitro and exploring the possibility of quercetin as functional feed additives. The datas will provide a theoretical basis for applying quercetin in livestock production. This study was summarized by four parts as belows:⑴Effects of quercetin on cecum bacteria in laying hensCompared with control, E. coli was significantly decreased by 0.04% and 0.06% quercetin(P<0.01). Staphylococcus aureus, Salmonella, Pseudomonas aeruginosa, E.faecalis, Enterococcus were decreased by quercetin(P<0.01, P<0.05, P<0.05, P<0.01, P<0.05). Lactobacillus had the increase trend(P=0.072). Bifidobacterium was increased by quercetin(P<0.05, P<0.01, P<0.05).⑵Bacteriostasis of quercetin on 8 of infected bacteria in poultry in vitroThe diameters of the inhibition zone of tested strains were significantly increased(P<0.01) with the increasing quercetin. E. Coli, Salmonella, Pasteurella, Proteusbacillus vulgaris and Pseudomonas aeruginosa are gram negative bacteria, Staphylococcus aureus, E. faecalis and Enterococcus are gram positive bacteria, the minimum inhibitory concentration and diameters of the inhibition zone of tested strains were considered overall, the bacteriostasis of quercetin on gram negative bacteria were better.⑶Comparison of bacteriostasis between quercetin and antibioticsSpecific antibiotics as positive control, regression curve was drawn between different concentrations of quercetin and diameters of the inhibition zone, the concentrations of antibiotics added to tested strains were higher than that of quercetin according to MIC, also, the concentrations of antibiotics were different with each other.⑷Bacteriostasis mechanism of quercetin on 4 of infected bacteria in poultry in vitroCompared with control, ultrastructure, structural integrity and cell membrane of tested strains were changed by quercetin, the endochylema contents of bacteria leakaged, then bacteria cavitated and died. The extracellular AKP content in E. faecalis had the increase trend(P=0.069) and the extracellular AKP in the other three strains was significantly increased(P<0.01) with the increasing quercetin. The level of β-galactose glucoside enzyme, concentration of soluble proteinin and ATP enzyme activity of tested strains(except for E. coli) were significantly increased(P<0.01) with the increasing quercetin.In conclusion, data from the experiment indicated that quercetin played a bacteriostasis role in vivo via increasing the beneficial bacteria(Bifidobacterium) and reducing harmful bacteria(E. Coli, Staphylococcus aureus, Salmonella, Pseudomonas aeruginosa, E. faecalis and Enterococcus) growth. In vitro, quercetin played a bacteriostasis role via affecting the cell wall and cell membrane.