Advances in Phytoremediation Research: A Case Study of Gynura Pseudochina (L.) DC.

Abstract

Phytoremediation is the process through which contaminated land is ameliorated by growing plants that have the ability to remove the contaminating chemicals. The processes in phytoremediation include phytodegradation, phytostabilization, phytovolatilization and rhizofiltration. In addition, the association of plant and microorganism in the rhizosphere seems to enhance removal of the contaminants. Although relatively slow, phytoremediation is environmentally friendly, cheap, requires little equipment or labor, is easy to perform, and sites can be cleaned without removing the polluted soil; it is an in situ method. In addition, precious metals, such as gold, zinc and chromium, collected by the hyperaccumulator can be harvested and extracted as phytoextraction. However, the key factor for successful phytoremediation is identification of a plant that is tolerant and suitable for each area, one which can accumulate high concentrations of the required metal. In addition, the mechanism of heavy metal accumulated in the plant should be studied before the application. Advance research in phytoremediation has been focused on the analysis of the distribution and speciation of metals accumulated in the hyperaccumulative plant by using synchrotron radiation and the techniques of micro-X-ray fluorescence imaging (µ-XRF imaging) and X-ray adsorption fine edge structure (XAFS). Expression of metal-inducible proteins in plant such as glutathione, methallothionine and heat-shock proteins have been extracted by various suitable extraction buffers, separated and purified by the techniques of dialysis, chromatography and gel electrophoresis. Then, the amino acid sequences, the crystal structures of proteins, and the status of the metal bound in the proteins have been studied. In addition, the microorganisms in the rhizosphere of metal hyperaccumulative plants have been investigated by isolating the bacteria that are tolerant to heavy metals and contain plant growth promoting properties; such as nitrogen fixation, phosphate solubilization, indole-3-acetic acid (IAA) phytohormone and 1-aminocyclopropane-1-carboxylate (ACC) deaminase production, etc. Finally, the plant design for successful phytoremediation in any contaminated area should be concerned with ground water, running off, geology and the effect of growing the plant on biodiversity. Especially, harvesting management and byproduct utilization should be studied and investigated to convince local people and government of the usefulness of phytoremediation.

Biotechnological advances in bioremediation of heavy metals contaminated ecosystems: an overview with special reference to phytoremediation

“…KK1 caused significant increase in the urease (334 %), DHO (dehydrogenase) (14 %) and phosphatase (37 %) activity in the bioaugmented mine soil in South Korea (Govarthanan et al 2013). In a phytoremediation process at a Zn-/Cd-contaminated mine area, Thailand, isolated Pseudomonas aeruginosa PDMZnCd2003 (bacterium) promoted the growth of G. pseudochina (L) DC and enhanced the extraction of polyphenolic compounds (containing antioxidant properties) from the plant's leaves (Nakbanpote et al 2010). Dowarah et al (2009) used an integrated approach to rejuvenate a high sulfur mine overburden dumping site in the Tirap Collieries, Assam, India (near Indo-Burma hot spot biodiversity region), using a variety of plant species.…”

The Capacity of Heavy Metal Remediation by Cyperus alternifolius, Chrysopogon zizanioides (L.) Roberty, and Aloe vera (L.) Burm.f. under Industrial and Urban Wastewater Treatment

“…Also, C. zizanioides and C. alternifolius accumulated more heavy metals in their roots than shoots, but A. vera collected more heavy metals in its shoot than root. This difference in the simultaneous accumulation of metallic elements of roots and stems can be caused by the difference in the absorption of metals by the roots and shoots of the plant depending on plant species, metal type, and bioavailability (Nakbanpote et al, 2010). Some heavy metals are easily translocated to shoots but the majority of heavy metals are stored in the roots of the plants.…”

A Brazilian Amazon Species with High Potential to Phytoextract Potential Toxic Elements

“…The effective uptake and transportation of Al and Fe in E. oleracea highlight the potential use of the species to phytoextract both elements from soils (Baker & Brooks, 1989). Essential features to introduce the E. oleracea in phytoremediation programs to remove pollutants from contaminated areas (Nakbanpote et al, 2010).…”