Role In Phytoremediation Research Articles

Editorial for special issue: Biomass and Energy Crops

Editorial for special issue: Biomass and Energy Crops

Effect of zinc and lead on the physiological and biochemical properties of aquatic plant Lemna minor: its potential role in phytoremediation

Plants have gained importance in situ bioremediation of heavy metals. In the present study, different concentrations of zinc (Zn2+) (0.5, 5, 10, 15, 20 mg/l) and lead (Pb2+) (1, 2, 4, 6, 8 mg/l) were used to evaluate metal tolerance level of Lemna minor. L.minor were exposed to metals for 4 days and tested for its dry to fresh weight ratio (DW/FW), photosynthetic pigments production and protein content. The oxidative damage was detected by measuring catalase activity. L.minor showed tolerance against Zn2+ and Pb2+ at a concentration of 10 and 4 mg/l, respectively. Among the metals, Pb2+ showed a significant toxicity at 8 mg/l. High concentration (20 mg/l of Zn2+ and 8 mg/l of Pb2+) of the metals displayed a considerable negative effect on soluble proteins (13 fold decrease with Zn2+ and 4 fold decrease with Pb2+) and photosynthetic pigments (twofold decrease with Zn2+ and onefold decrease with Pb2+) and lead to a consequent reduction in number of fronds. Further, the catalase was greatly increased (twofold decrease with Zn2+ and sixfold decrease with Pb2+) under metal stress. The results indicate that L.minor withstands Zn2+ and Pb2+ toxicity up to the concentration of 10 and 4 mg/l, respectively. Hence, the metal tolerant property of this plant shall be exploited for bioremediation of Zinc and Lead in polluted water. Further, the detailed and wide range of heavy metal toxicity studies should be done to reveal the possible use of this plant on large scale bioremediation purpose.

Active removal of ibuprofen by Money plant enhanced by ferrous ions

In this study, the removal of ibuprofen (IBP), a pharmaceutical compound, from aqueous media by Money plant (Epipremnum aureum) was investigated. The effect of ferrous iron (Fe2+) on enhancing the IBP removal rate was also analyzed. The first-order removal rate constants showed higher values for lower IBP initial concentrations in the range of 0.20–0.28 d−1 for an initial concentration of 125 μg L−1 to 0.03–0.13 d−1 for an initial concentration of 1000 μg L−1. Introducing ferrous iron to the aqueous media enhanced the first-order removal rate constant up to 6.5 times in a 3 d time period. Along with the removal of IBP from the media, the endogenous concentration of H2O2 also decreased presumably by the production of hydroxyl radical (OH). Reduction in the endogenous H2O2 concentration was recorded to be 38% and 98% in the absence and presence of Fe2+ respectively in the first day and the H2O2 level remained considerably low until day 7 which then gradually increased slightly. Simultaneous reduction of IBP and endogenous H2O2 concentration could be due to the reaction of IBP with OH and presumably OH production itself accelerated via Fenton reaction. In addition, presence of sodium bicarbonate (NaHCO3) as OH scavenger in the system showed reduction of first-order removal rate constant from 1.30 d−1 to 0.07 d−1 which could be a possible evidence of biological advanced oxidation process which is believed to play an important role in phytoremediation.

Phytoremediation capacity of aquatic plants is associated with the degree of phytochelatin polymerization

Phytochelatins (PCs) play important role in phytoremediation as heavy metal binding peptides. In the present study, the association between heavy metal removal capacity and phytochelatin synthesis was compared through the examination of three aquatic plants: Elodea canadensis, Salvinia natans and Lemna minor. In case of a Cd treatment, or a Cd treatment combined with Cu and Zn, the highest removal capacity was observed in L. minor. At the same time, E. canadensis showed the lowest removal capacity except for Zn. The heavy metal-induced (Cu+Zn+Cd) oxidative stress generated the highest ascorbate level in L. minor. Cd in itself or combined with the other two metals induced a 10–15-fold increase in the amount of ɣ-glutamylcysteine in L. minor while no or smaller changes were observed in the other two species. Correspondingly, the total PC content was 6–8-fold greater in L. minor. In addition, PCs with higher degree of polymerization were only observed in L. minor (PC4, PC6 and PC7) while PC2 and PC3 occurred in E. canadensis and S. natans only. The correlation analysis indicated that the higher phytoremediation capacity of L. minor was associated with the synthesis of PCs and their higher degree of polymerization.

Biomonitoring of metal contamination in estuarine ecosystem using seagrass.

Metals concentrations (As, Cd, Cu, Hg and Pb) in seawater, sediment and the seagrass (Enhalus acoroides) were analysed at Pulai River estuary, Johor Straits, Malaysia. In this research, Enhalus acoroides was used in order to find it’s efficiency in up taking metals with a role in phytoremediation. Seawater, sediment and Enhalus acoroides samples were collected, and data of Pearson’s correlation coefficients were analysed using SPSS 16 software. Results show that lead levels were the highest metal content in Enhalus acoroides (202 ± 102 μg/gDW), seawater (268 ± 190 μg/L) and sediment (248 ± 218 μg/gDW), compared to other metals. There was a positive correlation for metal concentrations between Enhalus acoroides and sediment, but no correlation was found between Enhalus acoroides with seawater at estuarine area may be caused by inconsistent metal concentrations in seawater due to the influences of tidal changes and stormy waves. This indicates that Enhalus acoroides is a species possessing the capabilities to uptake metals from sediment, and suitable to act as both a phytoremediator and biomonitor in estuarine ecosystems due to sharp sensitivity to variation in the environment.

Biofuel crops: production, physiology and genetics

<title>Abstract</title> This book begins with a review of the history of biofuel. It contains chapters that are devoted to emerging technologies for biofuel production, cell wall structure and destructing approaches, cellulosic biofuel crops role in phytoremediation, and feedstock pretreatment methods. Detailed discussion on the physiological and genetic research challenges and opportunities for the improvement of biofuel crops at large also constitutes a chapter. The book comprehensively covers taxonomy, genetics, breeding, physiology and biochemistry of algae and different technologies of their conversion to biofuel in view of the future potential of algal biofuel.

Role of Bacillus licheniformis in Phytoremediation of Nickel Contaminated Soil Cultivated with Rice

Heavy metal contamination in soil is an important environmental problem and it has negative effect on agriculture. Bacteria play a major role in phytoremediation of heavy metals contaminated soil. In this study, the effect of Bacillus licheniformis NCCP-59, a halophilic bacterium isolated from salt mines near Karak, Pakistan, were determined on a three week old greenhouse grown seedling and germinating seeds of two rice varieties (Basmati-385 (B-385) and KSK-282) in soil contaminated with different concentrations (0, 100, 250, 500, and 1000 ppm) of Nickel. Nickel significantly reduced the germination rate and germination percentage mainly at 500 and 1000 ppm. Significant decrease in ion contents (Na, K, and Ca) was observed while Ni ion concentration in the plant tissues increases as the concentration of Ni applied increases. The photosynthetic pigments (chlorophyll a (chl a), chlorophyll b (chl b), and carotenoids) were also decreased by the application of different concentrations of Ni. Total protein and organic nitrogen were found to be reduced at higher concentrations of Nickel. Inoculation of Bacillus Licheniformis NCCP-59 improved seed germination and biochemical attribute of the plant under Ni stress. It is clear from the results that the Bacillus Licheniformis NCCP-59 strain has the ability to protect the plants from the toxic effects of nickel and can be used for the phytoremediation of Ni contaminated soil.

Heavy metal tolerance and accumulation of Triarrhena sacchariflora, a large amphibious ornamental grass

In this study, we report the tolerance and accumulation of Triarrhena sacchariflora to copper (Cu) and cadmium (Cd). The results show that T. sacchariflora had strong tolerance to Cu and Cd stress. The tolerance indexes (TI) were greater than 0.5 for all treatments. The bioconcentration factors (BCFs) to Cu and Cd were both above 1.0. The accumulation ability of roots was stronger than that of shoots, and ranges of BCF to Cu and Cd in roots were 37.89-79.08 and 83.96-300.57, respectively. However, the translocation ability to Cu and Cd was weak, with more than 86% of Cu or Cd accumulated in roots, suggesting an exclusion strategy for heavy metal tolerance. The uptake efficiency (UE) and translocation efficiency (TE) to Cu and Cd increased linearly as the Cu and Cd concentration in the substrate increased. UE was higher than TE, with a maximum of 2,118.90 μg g(-1) root dry weight (DW) (50 mg L(-1) Cu) and 1,847.51 μg g(-1) root DW (20 mg L(-1)Cd), respectively. The results indicate that T. sacchariflora is a Cu- and Cd-tolerant non-hyperaccumulator plant, suggesting that T. sacchariflora could play an important role in phytoremediation in areas contaminated with Cu and Cd.

The Ecology of Arbuscular Mycorrhizal Fungi

Arbuscular mycorrhiza is a mutually beneficial biological association between species in the fungal phylum Glomeromycota and higher plants roots. The symbiosis is thought to have afforded green plants the opportunity to invade dry land ca 450 Ma ago and the vast majority of extant terrestrial plants retain this association. Arbuscular mycorrhizal (AM) fungi perform various ecological functions in exchange for host photosynthetic carbon that almost always contribute to the fitness of hosts from an individual to community level. Recent AM fungal research, increasingly delving into the ‘Black Box’, suggests that species in this phylum may play a key facilitative role in below-ground micro- and meso-organism community dynamics, even more perhaps, that of a bioengineer. The ubiquitous nature of the symbiosis in extant flora and the fact that variations from the AM symbiosis are recent events suggest that Glomeromycota and plant roots coevolved. This review considers aspects of AM fungal ecology emphasizing past and present importance of the phylum in niche to global ecosystem function. Nutrient exchange, evolution, taxonomy, phenology, below-ground microbial interaction, propagule dissemination, invasive plants interactions, the potential role in phytoremediation and some of the factors affecting AM fungal biology are discussed. We conclude that it is essential to include AM association in any study of higher plants in natural environments in order to provide an holistic understanding of ecosystems.

Lophiostoma arundinis . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Lophiostoma arundinis , a species considered to be a saprobic fungus, colonizing dead culm tissues. Some information on its dispersal and transmission and conservation status is given, along with details of its geographical distribution (USA (Georgia, North Dakota, Rhode Island, South Carolina), Asia (Japan, Pakistan and Thailand), Europe (Austria, Belgium, Czech Republic, Denmark, Estonia, France, Germany, Greece, Netherlands, Poland, Spain, Sweden, Switzerland and UK)). The primary host species is a major component of freshwater and brackish water aquatic ecosystems worldwide. It frequently forms extensive stands, and plays an important role in phytoremediation via nitrate and phosphorus absorption.

A Ca2+-Sensitive System Mediates Low-Affinity K+ Uptake in the Absence of AKT1 in Arabidopsis Plants

K(+) acquisition by Arabidopsis roots is mainly mediated by the high-affinity K(+) transporter AtHAK5 and the inward-rectifier K(+) channel AtAKT1. This model is probably universal to plants. Mutant plants lacking these two systems (athak5,atakt1) take up K(+) and grow when the external K(+) concentration is above a certain level, indicating that an additional transport system may compensate for the absence of AtHAK5 and AtAKT1. Here we describe that this alternative system is essential for providing sufficient K(+) to sustain growth of athak5,atakt1 plants. This system is especially sensitive to Ca(2+), Mg(2+), Ba(2+) and La(3+), it transports Cs(+) and its activity is reduced by cyclic nucleotides. These results suggest that a Ca(2+)-permeable voltage-independent non-selective cation channel, probably belonging to the cyclic nucleotide gated channel (CNGC) family, may provide the pathway for K(+) uptake in athak5,atakt1 plants. The genes encoding the two members of the CNGC family that have been described as mediating root K(+) uptake, AtCNGC3 and AtCNGC10, are not up-regulated in athak5,atakt1 plants, excluding overexpression of these genes as a compensatory mechanism. On the other hand, an increased driving force for K(+) in athak5,atakt1 plants due to a hyperpolarization of the membrane potential of its root cells is also discarded. The identification of this unknown system may provide tools to improve plant K(+) nutrition in conditions where AtAKT1 functionality is reduced, such as under salinity. In addition, this system may constitute an important pathway for accumulation of toxic cations such as Cs(+) or radiocesium ((137)Cs(+)), and could play a role in phytoremediation.

Cadmium tolerance and accumulation characteristics of mature flax, cv. Hermes: Contribution of the basal stem compared to the root

The potential of mature flax plants (cv. Hermes) to tolerate and accumulate cadmium (Cd) was studied to determine which part of the plant would be the key organ for phytoremediation purposes. After 4month-growth on sand substrate containing 0.1mM Cd in a greenhouse, the roots and stems were separated and the stems were divided into three parts. The effects of Cd were studied on growth parameters, histology and mineral nutrition. No visible toxic symptoms were observed. Tolerance-index values calculated from growth parameters and nutrients remained relatively high, allowing the development of the plant until maturity and formation of seeds. The roots and bottom stem accumulated the highest quantity of Cd (750 and 360mg/kg dry matter), values which largely exceeded the threshold defined for hyperaccumulators. On the other hand, basal stem had a high bioconcentration factor (BCF=32) and translocation factor TF′ (2.5) but a low TF (0.5), indicating that this basal part would play a major role in phytoremediation (phytostabilization rather than phytorextraction). Therefore, the high tolerance to Cd and accumulation capacity make possible to grow Hermes flax on Cd-polluted soils.

Effect of heavy metal and EDTA application on heavy metal uptake and gene expression in different Brassica species

The present study investigates the effect of different concentration of heavy metals (Cd, Cr and Pb) and ethylenediaminetetraacetic acid (EDTA) application on two Brassica species ( Brassica carinata and Brassica juncea ). EDTA application had significant (p<0.05) effect on shoot length, shoot fresh weight, shoot dry weight, root length, root fresh weight, root dry weight and accumulation of heavy metals in both species. Species also produced significant (p<0.05) effect on all parameters except shoot length of the plant. The effect of heavy metals on shoot length, shoot fresh weight, root fresh weight and accumulation of heavy metals was also reported to be significant (p<0.05). Interaction between heavy metals × species showed a significant (p<0.05) effect on shoot fresh weight, shoot dry weight, root length and accumulation of heavy metal in both Brassica species. The data reveal that maximum shoot length, shoot fresh weight, shoot dry weight, root fresh weight and root dry weight was achieved by control plants. In addition, maximum heavy metals (142.88 mg kg -1 ) were observed for B. juncea that were grown under 150 mg kg -1 Pb and 0 mM EDTA stress. Exposure of Brassica species to heavy metals and EDTA resulted in the expression of newly synthesized and abundantly expressed polypeptides, which may play a role in phytoremediation. Keywords: Brassica , phytoextraction, heavy metals, EDTA, gene expression

Endophytes and their role in phytoremediation

Many endophytes have been found to be resistant to heavy metals and/or capable of degrading organic contaminants, and endophyte-assisted phytoremediation has been documented as a promising technology for in situ remediation of contaminated soils. During the phytoremediation of heavy metals, the heavy-metal-resistant endophytes can enhance plant growth, decrease metal phytotoxicity, and affect metal translocation and accumulation in plants. For the phytoremediation of organic contaminants, endophytes can produce various enzymes to degrade organic contaminants and reduce both the phytotoxicity and evapotranspiration of volatile contaminants. This paper reviews the diversity of contaminant-resistant/degrading endophytes and their role in phytoremediation and discusses some issues that have been raised surrounding this area of research.

Phytoremediation of Metal-Polluted Soils by Arbuscular Mycorrhizal Fungi

Human activities generate wastes, some of which contain large amounts of heavy metals/metalloids that could enter natural ecosystems and alter the activities and functioning of soil micro- and macroorganisms. Microorganisms can adapt/resist to metal stress, and some of them are able to promote the plants establishment and therefore the phytoremediation process. In this context, the use of arbuscular mycorrhizal fungi (AMF), and their role in phytoremediation, has emerged as a new and interesting choice. In addition to AMF's well-known contribution to plant nutrient acquisition and growth, these fungi develop diverse mechanisms that encourage plants to grow in soils with high toxic metals concentrations. The authors are concerned about the AMF metal tolerance mechanisms and its role in the promotion of in phytoremediation processes.

Characterization of Chromium Toxicity in Food Crops and their Role in Phytoremediation

This study evaluates and compares the remediation potential of rapeseed, soybean and wheat plants for Cr contamination. Seedlings of rapeseed (Brassica campestris cv Pusa Gold), soybean (Glycine max cv Pusa 20) and wheat (Triticum aestivum cv HD 2402) were grown hydroponically and subjected to four levels of Cr treatment (T0: Control, T1: 50 μM, T2: 100 μM and T3: 200 μM). The treated plants exhibited extreme variations in their defence behaviour against Cr stress. The extent of oxidative stress caused by Cr was measured by the rate of lipid peroxidation.

Phytoremediation using an indigenous crop plant (wheat): the uptake of methyl parathion and metabolism of p-nitrophenol

Phytoremediation is an emerging technology for degradation of organophosphate pesticides. Rhizofiltration, soil microorganisms and rhizosphere play an important role in phytoremediation. For this purpose, experiments were carried out to analyze the pesticide uptake by plants and residue in the soil under controlled and experimental conditions. Organophosphate pesticide binds to both organic matter and antibiotic streptomycin. Streptomycin inhibits the activity of the enzyme ( p -nitrophenol 4-hydroxylase) extracted from root and shoot. The results obtained from UVvisible spectrophotometer were confirmed by HPLC analysis. Wheat plants enhanced uptake/degradation of methyl parathion, p -nitrophenol and hydroquinone in unsterilized soil by 64.85%, 94.7% and 55.8% respectively. Methyl parathion hydrolyzes to p-nitrophenol, which is further metabolized to hydroquinone with nitrite release. The enzyme pnitrophenol 4-hydroxylase is active as evidenced by release of nitrite by leaf and root extracts and also by the appearance of hydroquinone in the reaction mixture.

Role of Rhizobacteria in Reduction of Arsenic Uptake by Plants: A Review

Heavy metal pollution of soil is a significant environmental problem and has its negative impact on human health and agriculture. Arsenic (As) distribution and toxicology in the environment is the serious issue worldwide. Rice is the major staple food for people in West Bengal and Bangladesh, is the biggest sufferers of arsenic contamination, and so protecting crops is of major importance and serious issues at these places. Bioremediation is the application of living organisms or products, or the application of biological principles, to ameliorate adverse environmental condition. Rhizosphere, as an important interface of soil and plant, plays a significant role in phytoremediation of contaminated soil by heavy metals, in which, microbial populations are known to affect heavy metal mobility and availability to the plant through release of chelating agents, acidification, phosphate solubilization and redox changes, and therefore, have potential to enhance phytoremediation processes. Phytoremediation strategies with appropriate heavy metal-adapted Rhizobacteria have received more and more attention. Microbes may influence our needs directly or indirectly. Directly by their detoxification potentials and may be the source of bioremediation and genetic engineering. Their exploitation in arsenic remediation would be simplest phenomenon to protect crops from arsenic, as it blocks the entry of heavy metals. This article deals with the identification, characterization and bioremediation advances in effect and significance of As-resistant Rhizobacteria in phytoremediation of heavy metal contaminated soils to prevent the transport arsenic metal from root to shoot to prevent the uptake by plants. There is also a need to improve our understanding of the mechanisms involved in the transfer and mobilization of heavy metals by Rhizobacteria and to conduct research on the selection of microbial isolates from rhizosphere of plants growing on heavy metal contaminated soils for specific restoration programmes.

Growth, reproductive and photosynthetic responses to copper in the yellow-horned poppy, Glaucium flavum Crantz.

Glaucium flavum Crantz. is found in an anthropized coastal grassland at the joint estuary of the Tinto and Odiel rivers (SW Spain), growing under the influence of high levels of copper contamination derived from nearby petrochemical industries, with no obvious adverse affects on the performance of the plant. In addition, this species exhibits a series of ecological characteristics which may render it appropriate for use in the phytoremediation of contaminated areas. Nonetheless, the response of G. flavum to elevated copper concentrations has not been studied. A greenhouse experiment was conducted to investigate the effects of a range of Cu concentrations (0 to 47mmoll−1) on the growth, reproduction and photosynthetic performance of G. flavum, by measuring relative growth rate, fruit and seed production, chlorophyll fluorescence parameters, gas exchange and photosynthetic pigment concentrations. We also determined total copper, nitrogen, phosphorous, sulphur, calcium and magnesium concentrations. G. flavum survived with concentrations of up to 730mgCukg−1 DW in the leaves, when treated with 30mmolCul−1 (2000mgl−1). Quantum efficiency of PSII, net photosynthesis rate, as well as leaf Ca and Mg concentrations were all negatively affected by Cu concentrations greater than 9mmoll−1 in the nutrient solution. Our results indicate that the reduction in photosynthetic performance may be attributed to the adverse effect of excess Cu on the photosynthetic apparatus of the plant, both directly, via a decrease in pigment concentrations, and indirectly, via interference of Cu with Ca ions of PSII. Growth and seed production were only slightly affected by leaf tissue concentrations as high as 230mgCukg−1 dry mass, which suggests that this species could play an important role in phytoremediation of Cu-contaminated soils.

WHAT ARE THE BENEFITS OF PLANTS INDOORS AND WHY DO WE RESPOND POSITIVELY TO THEM?

WHAT ARE THE BENEFITS OF PLANTS INDOORS AND WHY DO WE RESPOND POSITIVELY TO THEM?