Effects of cowpea(Vigna unguiculata) root mucilage on microbial community response and capacity for phenanthrene remediation  

作　　者：Ran Sun Richard W.Belcher Jianqiang Liang Li Wang Brian Thater David E.Crowley Gehong Wei 

机构地区：[1]State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University [2]Department of Environmental Sciences, University of California at Riverside

出　　处：《Journal of Environmental Sciences》2015年第7期45-59,共15页环境科学学报（英文版）

基　　金：supported by the National High Technology Research and Development Program (863) of China (No. 2012AA100402);Cheung Kong Scholars Programme and the National Natural Science Foundation of China (Nos. 31125007 and 31370142)

摘　　要：Biodegradation of polycyclic aromatic hydrocarbons（PAHs） is normally limited by their low solubility and poor bioavailability. Prior research suggests that biosurfactants are synthesized as intermediates during the production of mucilage at the root tip. To date the effects of mucilage on PAH degradation and microbial community response have not been directly examined. To address this question, our research compared 3 cowpea breeding lines（Vigna unguiculata） that differed in mucilage production for their effects on phenanthrene（PHE） degradation in soil. The High Performance Liquid Chromatography results indicated that the highest PHE degradation rate was achieved in soils planted with mucilage producing cowpea line C1, inoculated with Bradyrhizobium, leading to 91.6% PHE disappearance in 5 weeks. In root printing tests, strings treated with mucilage and bacteria produced larger clearing zones than those produced on mucilage treated strings with no bacteria or bacteria inoculated strings. Experiments with14C-PHE and purified mucilage in soil slurry confirmed that the root mucilage significantly enhanced PHE mineralization（82.7%）, which is 12% more than the control treatment without mucilage. The profiles of the PHE degraders generated by Denaturing gradient gel electrophoresis suggested that cowpea C1, producing a high amount of root mucilage, selectively enriched the PHE degrading bacteria population in rhizosphere. These findings indicate that root mucilage may play a significant role in enhancing PHE degradation and suggests that differences in mucilage production may be an important criterion for selection of the best plant species for use in phytoremediation of PAH contaminated soils.Biodegradation of polycyclic aromatic hydrocarbons（PAHs） is normally limited by their low solubility and poor bioavailability. Prior research suggests that biosurfactants are synthesized as intermediates during the production of mucilage at the root tip. To date the effects of mucilage on PAH degradation and microbial community response have not been directly examined. To address this question, our research compared 3 cowpea breeding lines（Vigna unguiculata） that differed in mucilage production for their effects on phenanthrene（PHE） degradation in soil. The High Performance Liquid Chromatography results indicated that the highest PHE degradation rate was achieved in soils planted with mucilage producing cowpea line C1, inoculated with Bradyrhizobium, leading to 91.6% PHE disappearance in 5 weeks. In root printing tests, strings treated with mucilage and bacteria produced larger clearing zones than those produced on mucilage treated strings with no bacteria or bacteria inoculated strings. Experiments with14C-PHE and purified mucilage in soil slurry confirmed that the root mucilage significantly enhanced PHE mineralization（82.7%）, which is 12% more than the control treatment without mucilage. The profiles of the PHE degraders generated by Denaturing gradient gel electrophoresis suggested that cowpea C1, producing a high amount of root mucilage, selectively enriched the PHE degrading bacteria population in rhizosphere. These findings indicate that root mucilage may play a significant role in enhancing PHE degradation and suggests that differences in mucilage production may be an important criterion for selection of the best plant species for use in phytoremediation of PAH contaminated soils.

关 键 词：BIOREMEDIATION Mucilage PHYTOREMEDIATION PAH mineralization RHIZOSPHERE 

分 类 号：X17[环境科学与工程—环境科学] X592