5 research outputs found
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Phytoprotective influence of bacteria on growth and cadmium accumulation in the aquatic plant Lemna minor
Certain plants are known to accumulate heavy metals, and can be used in remediation ofpolluted soil or water. Plant-associated bacteria, especially those that are metal tolerant,may enhance the total amount of metal accumulated by the plant, but this process is stillunclear. In this study, we investigated metal enhancement vs. exclusion by plants, and thephytoprotective role plant-associated bacteria might provide to plants exposed to heavymetal. We isolated cadmium-tolerant bacteria from the roots of the aquatic plant Lemnaminor grown in heavy metal-polluted waters, and tested these isolates for tolerance tocadmium. The efficiency of plants to accumulate heavy metal from their surroundingenvironment was then tested by comparing L. minor plants grown with added metaltolerant bacteria to plants grown axenically to determine, whether bacteria associated withthese plants increase metal accumulation in the plant.Unexpectedly, cadmium tolerance was not seen in all bacterial isolates that had beenexposed to cadmium. Axenic plants accumulated slightly more cadmium than plantsinoculated with bacterial isolates. Certain isolates promoted root growth, but overall,addition of bacterial strains did not enhance plant cadmium uptake, and in some cases,inhibited cadmium accumulation by plants. This suggests that bacteria serve a phytoprotectiverole in their relationship with Lemna minor, preventing toxic cadmium from enteringplants
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Trace element analysis and speciation of selenium, arsenic and gold in biological materials
Methods for determination and speciation of inorganic and organic selenium in complex matrices involving, inductively-coupled plasma mass spectrometry (ICP-MS), inductively-coupled plasma atomic emission spectrometry (ICP-AES) and high performance liquid chromatography (HPLC) were developed. Selenium species were separated and detected by mixed-mode weak anion exchange and reversed-phase stationary phases with ICP-MS and ICP-AES detection. Selenium-containing nutritional supplements, wheat flour and selenized yeast, were analyzed and the major selenium species were identified and quantified by HPLC-ICP-MS equipped with a dynamic reaction cell (DRC). The quantification response factors for different selenium and sulfur compounds, analyzed by DRC-ICP-MS and ICP-AES were determined. Possible reasons for the obtained results were discussed. The effects of arsenic and selenium added simultaneously to the growth media of Helianthus annus (sunflowers), red sunflowers and Eichhornia crassipes (water hyacinths) were determined with respect to accumulation and metabolism. Total selenium and arsenic in shoots and roots was determined. Quantification of the selenium and arsenic species in E. crassipes by HPLC-ICP-MS and HPLC-ICP-AES was also performed. An accurate and reliable method was developed for the determination of functionalized gold nanoparticles in hepatocarcinoma cell tissues and rat brain material by ICP-MS. A comparison between the gold accumulated in cell and brain tissues treated with neutral, positive and negative functionalized gold nanoparticles was performed
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