title: Characterization of ACC deaminase-producing endophytic bacteria isolated from copper-tolerant plants and their potential in promoting the growth and copper accumulation of Brassica napus.
abstract: One hundred Cu-resistant-endophytic bacteria were isolated from Cu-tolerant plants grown on Cu mine wasteland, of which, eight Cu-resistant and 1-aminocyclopropane-1-carboxylate (ACC) deaminase-producing endophytic bacteria were obtained based on the ACC deaminase activity of the bacteria and characterized with respect to metal resistance, production of ACC deaminase, indole-3-acetic acid (IAA) as well as siderophores and mineral phosphate solubilization. Ralstonia sp. J1-22-2, Pantoea agglomerans Jp3-3, and Pseudomonas thivervalensis Y1-3-9 with higher ACC deaminase activity (ranging from 213 to 370 μM α-ketobutyrate mg(-1)h(-1)) were evaluated for promoting plant growth and Cu uptake of rape grown in quartz sand containing 0, 2.5, and 5 mg kg(-1) of Cu in pot experiments. The eight bacteria were found to exhibit different multiple heavy metal resistance characteristics, to show different levels of ACC deaminase activity and to produce indole acetic acid. Seven bacteria produced siderophores and solubilized inorganic phosphate. Pot experiments showed that inoculation with the strains (J1-22-2, Jp3-3, and Y1-3-9) was found to increase the biomass of rape. Increases in above-ground tissue Cu contents of rape cultivated in 2.5 and 5 mg kg(-1) of Cu-contaminated substrates varied from 9% to 31% and from 3 to 4-fold respectively in inoculated-rape plants compared to the uninoculated control. The maximum Cu uptake of rape was observed after inoculation with P. agglomerans Jp3-3. The results show that metal-resistant and plant growth promoting endophytic bacteria play an important role in plant growth and Cu uptake which may provide a new endophytic bacterial-assisted phytoremediation of Cu-contaminated environment.
authors.affiliation: MOA Key Laboratory of Microbiological Engineering of Agricultural Environment, College of Life Science, Nanjing Agricultural University, Nanjing 210095, PR China.
authors.forename: Yan-Feng
authors.initials: YF
authors.lastname: Zhang
authors.forename: Lin-Yan
authors.initials: LY
authors.lastname: He
authors.forename: Zhao-Jin
authors.initials: ZJ
authors.lastname: Chen
authors.forename: Qing-Ya
authors.initials: QY
authors.lastname: Wang
authors.forename: Meng
authors.initials: M
authors.lastname: Qian
authors.forename: Xia-Fang
authors.initials: XF
authors.lastname: Sheng
mesh_terms: D000222:Adaptation, Physiological; D001419:Bacteria / Q000145:classification / Q000201:enzymology* / Q000235:genetics; D001483:Base Sequence; D029688:Brassica napus / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology*; D019755:Carbon-Carbon Lyases / Q000378:metabolism*; D003300:Copper / Q000378:metabolism / Q000633:toxicity*; D007210:Indoleacetic Acids / Q000378:metabolism; D008969:Molecular Sequence Data; D012989:Soil Pollutants / Q000378:metabolism / Q000633:toxicity*
chemical_list: D007210:Indoleacetic Acids; D012989:Soil Pollutants; C030737:indoleacetic acid; D003300:Copper; C033634:1-aminocyclopropane-1-carboxylate deaminase; D019755:Carbon-Carbon Lyases