The Rhizosphere Microbial Ecology Of Potamogeton Crispus And Its Effect On Removal Of Phthalate Esters

In this thesis, Potamogeton crispus, which is a kind of typical submerged plant in the Haihe River, was selected. Dibutyl phthalate (DBP) and di-ethylhexyl phthalate (DEHP), two kinds of phthalates esters (PAEs) which were listed as'priority persistent organic pollutants'by the US EPA and China, were selected as typical contaminants. The removal of DBP and DEHP in rhizosphere of Potamogeton crispus was studied by stimulating laboratory experiments and the phospholipid fatty acid (PLFA) analysis were used to investigate rhizosphere microbial ecology of Potamogeton crispus.The results showed that under the condition of 25℃, 3000 Lux light intensity and irradiation time of 12 h.d-1, the use of MS medium containing 3% sucrose, 0.8% agar, 1.0-3.0 mg.L-1 6-BA and 0.5 mg.L-1 IBA successfully induced Potamogeton crispus adventitious buds, while the MS medium containing 2% sucrose and 2.0 mg.L-1 IBA was a good select for inducing Potamogeton crispus roots. Three methods, including continuous root exudates trapping system (CRETS), static resin and hydroponic culture, were chosen to collect and separate root exudates. The results showed that static resin was than CRETS and AB-8 was better than D4020. Hydroponic culture was the best method to collect and separate root exudates in consideration of the classes and quantities of separation.Phthalates had an affect on the classes and quantities of the Potamogeton crispus root exudates. Some of the isolated root exudates are common found in reports, such as caffeic acid, nonanoic acid, hexadecanoic acid, octadecanoic acid, maleic acid, hexanedioic acid, 4-hydroxybenzoic acid and 2,5-dihydroxybenzoic acid. These exudates will affect the physicochemical property of the rhizosphere soil, pollutant transfer and the microbial communities if they be excreted to the rhizosphere.Under the sterile condition, DBP was easier biodegradable than DEHP. The degradation half-life of DBP and DEHP were 4.1 and 12 d, respectively. Microorganisms play the major effect on degradation of DBP and DEHP. TOC in rhizosphere of Potamogeton crispus was lower than that in the non-rhizosphere. DBP, DEHP, MBP, and MEHP are easier to concentrate in the Potamogeton crispus roots than in stems and leaves. Phthalate esters could significantly affect rhizosphere microbial community (SMC) structure and functioning. PLFAs can be analyzed with multivariate procedures to determine statistically significant changes in SMC structure and relative abundances from rhizosphere soils under stress of Phthalate esters.