Inhibitory Effects Of Wetland Plant Extract On Pathogenic

The discovery of antibiotics is one of the great achievements in the field of medicine.Antibiotics has played an important role in the improvement of human health and the guarantee of life safety,and played a positive role in promoting the development of aquaculture.However,in recent years,there are lots of problems in aquaculture,such as the residues of antibiotics in animals induced by the neglect of the dosage,the medication times and the withdrawal period of antibiotics when it was used Meantime,the excessive intake of antibiotics or residue of antibiotics in food made it concentrate in human body and attenuated its effect on pathogenic bacteria.So,it is urgent to find other natural disinfectant to replace antibiotics.Wetland plants may have a unique role in resisting pathogenic microorganisms due to the particularity of their living environment Therefore,this research selected 36 species of wetland plants as subject,they were Phragmites australis,Alternanthera philoxeroides,Eichhornia crassipes,Nelumbo nucifera,Trapa bispinosa,Vallisneria natans,Euryale ferox,Polygonum hydropiper,P.lapathifolium,.Jucundum,Acorus calamus,Potamogeton crispus,P.malaianus,Salvinia natans,Ceratophyllum demersum,Monochoria vaginalis,Hydrilla verticillata,Hydrocharis dubia,Oenanthe javanica,Pisitia stratiotes,Herba Taraxaci,Commelina communis,Solanum nigrum,Lysimachia christinae,Rubia cordifolia Linn,Stellaria media,Oxalis pescaprae,Zizania latifolia,Portulaca oleracea,Ranunculus sieboldii,Kyllinga brevifolia,Eleusine indica,Glechoma longituba,Equisetum ramosissimum,Spiranthes sinensis,Alopecurus aequalis.Their active ingredients were extracted by water and ethanol.And the antimicrobial activity of extrcts against seven kinds of bacteria,such as Staphylococcus aureus,Escherichia coli,Pseudomonas aeruginosa,Salmonella typhimurium,Aeromonas hydrophila,Aeromonas aeruginosa and Vibrio parahaemolyticus,was detemined.Then,the plant extracts with high antibacterial activity were screened and purified by different solvent extraction.Finally,the plant extracts with the highest bacteriostatic ability were added to the food of Procambarus clarkii to obsever the effect of these extractsa on the survival rate and non-specific immunity of Procambarus clarkii,So,the results of this research would be helpful to find new way to control bacterial diseases and be benefit to apply safe additives in animal food.The results were as follows.1.The ethanol extracts of 36 plants inhibited different bacteria.The extaracts of Trapa bispinosa,Euryale ferox,Polygonum hydropiper,Solanum nigrum,Rubia cordifolia,Ranunculus sieboldii and Spiranthes sinensis had a certain inhibitory effect on Escherichia coli.And the extracts of Trapa bispinosa,Euryale ferox,Polygonum hydropiper,Solanum nigrum,Rubia cordifolia,Ranunculus sieboldii,Spiranthes sinensis and Pisitia stratiotes could inhibit Staphylococcus aureus.The plants which could inhibit the growth of Salmonella typhimurium are Trapa bispinosa,Euryale ferox,Solanum nigrum and Rubia cordifolia.And the extracts of Trapa bispinosa,Euryale ferox,Polygonum hydropiper,Solanum nigrum,Rubia cordifolia and Spiranthes sinensis could inhibit Pseudomonas aeruginosa.Aeromonas hydrophila was inhibited by the extracts of Alternanthera philoxe.roides,Trapa bispinosa,Monochoria vaginalis,Rubia cordifolia,Portulaca oleracea,Spiranthes sinensis,Ranunculus sieboldii,Glechoma longituba,Ceratophyllum demersum and Pisitia stratiotes.Aeromonas sobria was inhibited by the extracts of Alternanthera philoxeroides,Trapa bispinosa,Polygonum hydropiper,Solanum nigrum,Rubia cordifolia,Spiranthes sinensis,Portulaca oleracea,Ranunculus sieboldii and Glechoma longituba.The extracts of Alternanthera philoxeroides,Trapa bispinosa,Solanum nigrum,Lysimachia christinae,Rubia cordifolia,Portulaca oleracea,Ranunculus sieboldii and Glechoma longituba inhibited the growth of Vibrio parahemolyticus.2.The antibacterial effect of water extraction is less than that of ethanol extract.The minimal inhibitory concentration of Spiranthes sinensis water extraction against to Escherichia coli was 200 mg·mL-1,and its inhibition zone diameter was 12.38 mm.The water extracts of Alternanthera philoxeroides,Euryale ferox,Herba Taraxaci,Solanum nigrum,Stellaria media,and Spiranthes sinensis had a certain inhibitory effect on Aeromonas hydrophila.And the water extracts of Alternanthera philoxeroides,Monochoria vaginalis,Herba Taraxaci,Stellaria media,Glechoma longituba,Spiranthes sinensis inhibited Aeromonas sobria.Vibrio parahemolyticus was inhibited by water extracts of Alternanthera philoxeroides,Monochoria vaginalis,Spiranthes sinensis,Stellaria media,Glechoma longituba and Solanum nigrum.3.The ethanol extracts of Trapa bispinosa,Euryale ferox,Solanum nigrum,Rubia cordifolia were extracted with other solvent because of their higher antibacterial activity.And we found that the ethyl acetate extract of Trapa bispinosa had obvious antibacteria effect.When its concentration is 200 mg·ml^-1,its antibacteria diameter was 26.38 mm to Staphylococcus aureus and 27 mm to Vibrio parahaemolyticus,respectively.The inhibition zone diameter of 1.00%chloramphenicol was 25.73 mm to Staphylococcus aureus and 25.25 mm to Vibrio parahaemolyticus,respectively.So it indicated that the antibacterial effect of Trapa bispinosa ethyl acetate extract was significantly higher than that of 1.00%chloramphenicol.4.The content of total protein,activities of alkaline phosphatase and acid phosphatase in the ethanol extract group was significantly higher than those of the control group and 1.00%chloramphenicol group when added the ethyl acetate extract of Trapa bispinosa to the food of Procambarus clarkii for 15 days late,and it could improve the survival rate of Procambarus clarkii.The results showed that the antibacterial activity of the active ingredients was different according to the methods they were extracted and the antibacterial activity of the alcohol extract was higher than that of the water extract.The ethanol extract of Trapa bispinosa,Euryale ferox,Polygonum hydropiper,Pisitia stratiotes,Solanum nigrum,Rubia cordifolia,Spiranthes sinensis,Alternanthera philoxeroides,Monochoria vaginalis,Portulaca oleracea,Glechoma longituba,Ceratophyllum demersum,Herba Taraxaci,Stellaria media,Lysimachia christinae had a certain antibacterial effect.The ethyl acetate extract of Trapa bispinosa had the best antibacterial activity and could enhance the immunity and survival rate of Procambarus clarkii.