title: Analysis and characterization of cultivable heavy metal-resistant bacterial endophytes isolated from Cd-hyperaccumulator Solanum nigrum L. and their potential use for phytoremediation.
abstract: This study investigates the heavy metal-resistant bacterial endophytes of Cd-hyperaccumulator Solanum nigrum L. grown on a mine tailing by using cultivation-dependent technique. Thirty Cd-tolerant bacterial endophytes were isolated from roots, stems, and leaves of S. nigrum L. and classified by amplified ribosomal DNA-restriction analysis into 18 different types. Phylogenetic analysis based on 16S rDNA sequences showed that these isolates belonged to four groups: Actinobacteria (43%), Proteobacteria (23%), Bacteroidetes (27%) and Firmicutes (7%). All the isolates were then characterized for their plant growth promoting traits as well as their resistances to different heavy metals; and the actual plant growth promotion and colonization ability were also assessed. Four isolates were re-introduced into S. nigrum L. under Cd stress and resulted in Cd phytotoxicity decrease, as dry weights of roots increased from 55% to 143% and dry weights of above-ground from 64% to 100% compared to the uninoculated ones. The total Cd accumulation of inoculated plants increased from 66% to 135% (roots) and from 22% to 64% (above-ground) compared to the uninoculated ones. Our research suggests that bacterial endophytes are a most promising resource and may be the excellent candidates of bio-inoculants for enhancing the phytoremediation efficiency.
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha, People's Republic of China. sllou@hnu.cn
authors.forename: Sheng-lian
authors.initials: SL
authors.lastname: Luo
authors.forename: Liang
authors.initials: L
authors.lastname: Chen
authors.forename: Jue-liang
authors.initials: JL
authors.lastname: Chen
authors.forename: Xiao
authors.initials: X
authors.lastname: Xiao
authors.forename: Tao-ying
authors.initials: TY
authors.lastname: Xu
authors.forename: Yong
authors.initials: Y
authors.lastname: Wan
authors.forename: Chan
authors.initials: C
authors.lastname: Rao
authors.forename: Cheng-bin
authors.initials: CB
authors.lastname: Liu
authors.forename: Yu-tang
authors.initials: YT
authors.lastname: Liu
authors.forename: Cui
authors.initials: C
authors.lastname: Lai
authors.forename: Guang-ming
authors.initials: GM
authors.lastname: Zeng
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D001673:Biodegradation, Environmental; D018533:Biomass; D002104:Cadmium / Q000378:metabolism; D019216:Metals, Heavy / Q000378:metabolism*; D010802:Phylogeny; D018515:Plant Leaves / Q000382:microbiology; D018517:Plant Roots / Q000254:growth & development / Q000382:microbiology; D018547:Plant Stems / Q000382:microbiology; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017423:Sequence Analysis, RNA; D012989:Soil Pollutants / Q000378:metabolism*; D032324:Solanum nigrum / Q000254:growth & development / Q000382:microbiology*
chemical_list: D019216:Metals, Heavy; D012336:RNA, Ribosomal, 16S; D012989:Soil Pollutants; D002104:Cadmium