The Inhibition Of Hydrophytes Allelochemicals On Coliphage

Water resources are important natural resources, and are one of the controlling factors of the ecological environment. With the development of human society and economic, mankind's increasing demand for water resources. Rural sewage has become an important factor in natural waters pollution. Due to the advantages: simple process, low energy consumption, easy management and so on, constructed wetland water purification system become one of the best sewage treatment processes. Sewage may carry pathogens that could affect human health, and traditional disinfection processes are difficult to bring into effect in constructed wetland system. The purpose of the paper is based on coliphage T4 and f2 for model organisms, and chooses hydrophyte which has a strong ability to inhibit virus to isolate allelochemicals. At the same time, study the major organic acids of hydrophytes roots inhibit the ability of the virus, and provide the scientific basis for the use of hydrophytes allelochemicals reducing the concentration of virus in constructed wetlands.Double agar overlay (DAL) method was used to test the inhibition of extracts from hydrophytes on coliphages growth by the plaque forming unit (PFU) assay. Study was made on the allelopathy effect on two coliphages T4 and f2 growth caused by extracts from the different parts of five hydrophytes (Polygonum hydropiper, Polygonum orientale, Phragmites communis, Arundo donax and Typha latifolia). The result shows that the Polygonum hydropiper root shows the greatest inhibition and the EC50 on coliphage T4 of Polygonum hydropiper root was 0.6 mg·L-1,and the EC50 on coliphage f2 was 7.6 mg·L-1( press Total Oxygen Carbon (TOC)).Using liquid-liquid extraction method extracted and separated allelochemicals from P. hydropiper root and the allelochemicals can inhibit the growth of coliphage. Using gas chromatography - mass spectrometry identified the major components. Five solvents (petroleum ether, chloroform, ethyl acetate, n-butanol and distilled water) extractive parts showed that inhibition rate of saturated n-butanol phase (fraction D) on coliphage T4 and f2 was the strongest, and next was the ethyl acetate phase (fraction C). The purchase of 5 kinds of allelochemicals verified the inhibitory effect on coliphage,and the results showed that inhibition rate on coliphage was lower than 40% when the concentration of 4 kinds of allelochemicals were 10 mg/L.The inhibition effect of 11 kinds of organic acids (fumaric acid, maleic acid, tartaric acid, malic acid, succinic acid, citric acid, oxalic acid, lactic acid, acetic acid, caffeic acid and chlorogenic acid) on coliphage was discussed. The results showed that the inhibition rate of tartaric acid on coliphage T4 was the best, and the EC50 was 0.13 mg·L-1. Next was oxalic acid and the EC50 was 0.18 mg·L-1. The inhibiton rate of maleic acid on coliphage f2 was the best, and the EC50 is 0.33 mg·L-1. Next was fumaric acid, and the EC50 was 0.47 mg·L-1. The experiment of combined with organic acids showed that the combined effect of tartaric acid and oxalic acid was additive effect, and fumaric acid and maleic acid was also additive effect.The future research is to isolate the allelochemicals of Polygonum hydropiper root, and deeply disguss the inhibitory mechanism. The organic acids of root secretion on coliphage should be discussed.