title: [Effects of ryegrass (Lolium perenne) root exudates dose on pyrene degradation and soil microbes in pyrene-contaminated soil].
abstract: By simulating a gradually decreasing concentration of root exudates with the distance away from root surface in rhizosphere, this paper studied the effects of ryegrass (Lolium perenne) root exudates dose on the pyrene degradation and microbial ecological characteristics in a pyrene-contaminated soil. It was observed that with the increasing dose of ryegrass root exudates, the residual amount of soil pyrene changed nonlinearly, i. e. , increased after an initial decrease. When the root exudates dose was 32.75 mg kg(-1) of total organic carbon, the residual pyrene was the minimum, indicating that the root exudates at this dose stimulated pyrene degradation significantly. In the meantime, soil microbial biomass carbon and microbial quotient had an opposite trend, suggesting the close relationship between pyrene degradation and soil microbes. In the test soil, microbial community was dominated by bacteria, and the bacteria had the same variation trend as the pyrene degradation, which indicated that the pyrene was degraded mainly by bacteria, and the effects of root exudates on pyrene degradation were mainly carried out through the effects on bacterial population. There was a similar variation trend between the activity of soil dehydrogenase, a microbial endoenzyme catalyzing the dehydrogenation of organic matter, and the soil microbes, which further demonstrated that the variations of soil microbes and their biochemical characteristics were the ecological mechanisms affecting the pyrene degradation in the pyrene-contaminated soil when the ryegrass root exudates dose increased.
authors.affiliation: Center of Experiment Teaching, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China. xiexiaomei@zju.edu.cn
authors.forename: Xiao-mei
authors.initials: XM
authors.lastname: Xie
authors.forename: Min
authors.initials: M
authors.lastname: Liao
authors.forename: Jing
authors.initials: J
authors.lastname: Yang
mesh_terms: D001673:Biodegradation, Environmental; D008129:Lolium / Q000378:metabolism*; D053147:Plant Exudates / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology*; D018517:Plant Roots / Q000378:metabolism; D011721:Pyrenes / Q000302:isolation & purification / Q000378:metabolism*; D058441:Rhizosphere; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D053147:Plant Exudates; D011721:Pyrenes; D012989:Soil Pollutants; C030984:pyrene