| Serious heavy metal pollution events happened in the world since the 20th century, which not only harmed the human health and caused economic losses, also destroyed the ecological environment. The heavy metal in soil had the characteristics of persistence, elusive, irreversibility and difficult degradability. Physical, chemical and biological remediation are the useful methods in the restoration of polluted soils, in which biology remediation, especially hyperaccumulators of phytoremediation, was cost-efficient, eco-friendly and easy to be operated on a large scale without destroying the soil structure, has been considered the most promising technology. However, phytoremediation requires hyperaccumulators with high biomass and accumulating more amounts of metals. So we need to search more resource of wild plant, in addition, enhancing the absorption of plant to heavy metal by adding chemicals, microbial or fertilizer in soil. Among these methods, the least environmental risk and economic costs is adding microbial. Therefore, joint remediation of microbial and plant has been the focus on repairing heavy metal contamination.Copper is the essential element for life, but excessive amounts of copper will produce serious harmness to organism. Copper is one of the important pollution elements in China, because of many reasons, most of which have not been effective governance. It has important theoretical and practical significance for enriching bioremediation theory, strengthening the construction of ecological environment to screen copper patient resource and research joint remediation technology of plants and microorganisms. In the study, we identified the accumulated mechanisms of castor (Ricinus communis L.) which collected from an abandoned copper or iron mine in Tonglu Mountain, which is located in Daye City of Hubei Province, China, to copper in soil; and the patience mechanisms of strain TLSB3-K separated from the rhizosphere soil of castor, combining the technology of AAS, TEM, FTIR, HPLC, et al.. and the enhance effect of TLSB3-K to R. communis L. repairing copper contaminated soil. The conclusion was included that:The copper and cadmium belonged to heavy pollution grade, the copper was the typical pollution elements in Tonglu Mountain. The copper concentration in castor was highest than other heavy metal, mean was 2019.04 mg/kg (dry weight, the same below). The result showed that the plant revealed the strong ability of copper patience, which can not only growth normally in the heavily polluted soil, also accumulated large amount of copper, had the big potential to utilizing as the material of phytoremediation.The R. communis L. was exhibiting strong patience to copper in hydroponic conditions, too. When copper concentration was 40 mg/kg, the growth rate (GR) and biomass index (BMI) of the seedlings were up to the biggest value. The concentration was 60 mg/kg, the copper content of plant reached up to the highest 16570.12 mg/kg, and 91.31% of copper accumulated in root. Besides,67.66% of the copper in the root cells of castor seedlings were found binding to components of cell walls, such as exchangeable acidic polar compounds, cellulose, lignin, protein and pectin, with smaller amounts in cytoplasm and nuclei; the root cell wall thickened and a lot of high density electronic body gathered on it by TEM observation; FTIR resulted the carboxyl and hydroxyl of polysaccharide and amino of protein were the main binding sites of copper in the cell wall. The result above indicated that root cell walls play the major role in copper accumulation and detoxication in castor roots.The secretions of castor root were detected oxalic acid, lactic acid, citric acid, tartaric acid and malic acid by HPLC in potted experiment. When the copper concentration was less than 300 mg/kg, the secreting of lactic acid, citric acid, tartaric acid and malic acid were promoted, then, the copper inhibited the secreting of organic acid. The content of oxalic acid and malic acid accounted for 71.47% of total organic acids, had extremely significant linear positive correlation with content of copper in plant, which could play the positive role in copper absorption.Acid phosphatase in soil exhibited being actively under copper stress in potted experiment, and enzyme activity increased with the concentration of copper, when it was 900mg/kg, enzyme activity increased by 118.63%. the activity of urease, catalase and sucrase in soil were inhibited, the strength were sucrase> urease> catalase. The result showed the acid phosphatase in soil may be playing important effect in the copper absorption and transport in plant.Five strains of bacteria and five fungi were separated and screened from rhizosphere soil of castor. The bacteria were identified with 4 family and 4 species:Stenotrophomonas maltophilia, Bacillus cereus, Acinetobacter calcoaceticus, Pseudomonas putida. the fungi belonged to 3 family and 5 species:Penicillium marneffei, Aspergillus niger, Aspergillus flavipes), Aspergillus versicolor, Fusarium oxysporum.Strain TLSB3-K screened from the above 10 strains, had the strongest patience to copper. The optimum growth conditions and growth curve were discussed. According to the result, we found when the copper concentration was less than 500mg/kg, the bacteria growth was not effect obviously, but more than 500mg/kg, the bacteria growth was serious inhibition.Strain TLSB3-K had strong ability of adsorption the copper. Langmuir and Freundlich equation fitted the date, the R2 were 0.9230 and 0.9874 respectively, which showed the Freundlich equation was more suitable to describe the adsorption process. Adsorption kinetics was fitted by the Elovich equation, the result concluded that in the process of absorption, copper was not only combined on the surface of cell wall, also transferred to the intracellular and accumulated effect. The FTIR confirmed the hydroxyl, carboxylic, amides and phosphoryl group of cell wall polysaccharide and protein were the main binding site.The total protein of strain TLSB3-K was extracted, then 2-DE electrophoresis, gel printing and Maldi-TOF-TOF analysis were followed. The conclusion found the naturalized strain expressed the Antioxidants, antioxidant enzymes and resistance protein to enhance the patience to copper, which was the process of active defense.The enhancement effect of adding bacteria to the copper-contaminated soil collected from Tonglu Mountain in potted experiment. The result suggested that biomass and chlorophyll (especially chlorophyll a) content was promoted. Antioxidase of SOD、POD in plant were obviously activated, but the intensity of effect was weakness over the time. The malic acid, oxalic acid and tartaric acid secretion of plant root were also accelerated. The activation intensity of urease in soil gradually weakened, Catalase, phosphatase and sucrase were activated before suppressed. The copper concentration in castor was 25.70% higher than control, which shows a great enhancement effect. |
PDF Full Text Request