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The New Symbiotic Architecture
Published in Kyoung Hee Kim, Microalgae Building Enclosures, 2022
Biosorption, Bioaccumulation, and Biodegradation of Heavy Metals: Biosorption is defined as passive heavy metal uptake and relies on pollutant attachment on nonliving algal cell walls.51 Exposure to heavy metals causes detrimental health impacts and damages the function of internal organs. Common heavy metals found in building materials include lead, arsenic, cadmium, chromium, and mercury used for paint, insulation, metal coating, batteries, and power plants. Bioaccumulation is called active biosorption and has a two-step active process: (1) Active mechanisms transport metal ions into the cells and (2) heavy metals become attached to the surface of the algae.52 Uptake of heavy metals occurs through metabolism of metal ions absorbed and transported inside the cells. Phytochelatins are chemical compounds in microalgae that can help bind and detoxify heavy metals.53
Prospects for Exploiting Microbes and Plants for Bioremediation of Heavy Metals
Published in Maulin P. Shah, Removal of Refractory Pollutants from Wastewater Treatment Plants, 2021
Hiren K. Patel, Rishee K. Kalaria, Divyesh K. Vasava
In heavy metals toxicity, glutathione acts as a matter sequestration and relieving the aerophilous stress caused by metals. Researchers found an increase within the reduced sort of GSH up to 30 fold against cadmium (Cd+2) toxicity in Phragmites Australis (Pietrini et al., 2009). However, in some reports no such incremented GSH synthesis was ascertained, which may conclude that glutathione has no direct role in heavy metal detoxification, and acts through the formation of Phytochelatins. Phytochelatins have a role in the detoxification of heavy metals in plants, as they do in different organisms, where they acts as matter to bind with these heavy metals to create complexes that are signaled for compartmentalization. The term “Phytochelatin” is also related to microorganisms. They're additionally said to be found in roundworm C. elegans, slime molds Dictyostelium, and aquatic midge Chironomus oppositus, as reviewed by Cobbett (2000).
Metal Hyperaccumulator Plants: A Review of the Ecology and Physiology of a Biological Resource for Phytoremediation of Metal-Polluted Soils
Published in Norman Terry, Gary Bañuelos, of Contaminated Soil and Water, 2020
Alan J. M. Baker, S. P. McGrath, Roger D. Reeves, J. A. C. Smith
Phytochelatins are low-molecular-weight, cysteine-rich peptides (Rauser, 1995; Zenk, 1996) now designated class III metallothioneins, as they can be regarded generically as nontranslationally synthesized metal-thiolate polypeptides (Robinson et al., 1993). They are synthesized by representatives of the whole plant kingdom upon exposure to heavy metals (Grill et al., 1987), and they are especially produced by plants growing in metal-enriched ecosystems (Grill et al., 1988). Phytochelatins are believed to be functionally analogous to the metallothioneins produced by animals and fungi (Tomsett and Thurman, 1988; Robinson et al., 1993) and consequently to be involved in cellular homeostasis of metal ions. They have the ability to bind a wide range of metals and it has been suggested by some researchers (Jackson et al., 1987; Salt et al., 1989) that phytochelatins are directly involved in heavy metal tolerance. However, there is considerable evidence to contradict this view. Metal induction of phytochelatins has been observed in both metal-resistant and metal-sensitive plants (Schultz and Hutchinson, 1988; Verkleij et al., 1991; Harmens et al., 1993). Furthermore, buthionine sulfoximine (BSO), an inhibitor of phytochelatin synthesis, has been shown not to decrease zinc tolerance (Reese and Wagner, 1987; Davies et al., 1991), while sulfur deficiency was seen to have no effect on copper tolerance of Deschampsia cespitosa (Schultz and Hutchinson, 1988). It is therefore questionable what exact role phytochelatins play in cellular metal-tolerance mechanisms.
Interactions between cadmium and nutrients and their implications for safe crop production in Cd-contaminated soils
Published in Critical Reviews in Environmental Science and Technology, 2023
Ya Xin Zhu, Yao Zhuang, Xiao Hang Sun, Shao Ting Du
In addition to its uptake process, the translocation and storage of Fe also affect Cd accumulation in different plant organs. The loss-of-function of OPT3, an Fe2+ unloading transporter from xylem to phloem, decreased Fe concentration while increased Cd concentration in seeds compared with wild-type plants (Zhai et al., 2014). Plants have evolved a set of elaborate mechanisms to avoid the toxicity of heavy metals, including vacuole compartmentalization and complexation with thiol-rich peptides known as phytochelatins (Ahmad et al., 2019). Vacuoles are important Fe storage organelles in plants. In A. thaliana, NRAMP3 and NRAMP4 transport Fe from the vacuole to the cytoplasm. Previous studies have shown that disruption of AtNRAMP3 function leads to slightly enhanced Cd resistance during root growth, and overexpression of AtNRAMP3 resulted in Cd hypersensitivity of A. thaliana root growth and increased accumulation of Fe (Pottier et al., 2015). Ferritin, a special protein involved in Fe storage by directly binding to Fe2+, is ubiquitous in plants and thus contributes to the maintenance of Fe homeostasis. However, the Fe2+ bound to ferritin is easily replaced by Cd2+ owing to the similar hydrated ionic radii, and this kind of substitution will inevitably result in Fe deficiency (Sharma et al., 2021), along with a possible decrease in the availability of Cd2+ in plants. Therefore, it might be possible to control the availability of Cd in plants by regulating the genes related to intracellular Fe storage.
Involvement of glutathione and glutathione metabolizing enzymes in Pistia stratiotes tolerance to arsenite
Published in International Journal of Phytoremediation, 2020
Fernanda Vidal de Campos, Juraci Alves de Oliveira, Adinan Alves da Silva, Cleberson Ribeiro, Sebastián Giraldo Montoya, Fernanda dos Santos Farnese
Glutathione acts on different lines of defense to attenuate damages triggered by As, including dissipation of reactive oxygen species (ROS), ascorbate-glutathione cycle and the reduction of arsenate into arsenite (Zagorchev et al.2013; Singh et al.2015; Abbas et al.2018). These reactions involve the participation of important antioxidant enzymes, such as glutathione reductase (GR) and glutathione peroxidase (GPX). Glutathione also acts as a substrate for the synthesis of phytochelatins. Both phytochelatins and glutathione are able to form conjugates with metalloids, which are transported to the vacuole, where they accumulate without damaging plant cells (Seth et al.2012; Abbas et al.2018). The various metabolic pathways involved in glutathione metabolism, such as oxidation, synthesis, degradation and transport are essential to ensure plant tolerance to As (Hernández et al.2015).
Effect of two biodegradable chelates on metals uptake, translocation and biochemical changes of Lantana Camara growing in fly ash amended soil
Published in International Journal of Phytoremediation, 2018
Shikha Kumari Pandey, Tanushree Bhattacharya
Protein content (Figure 6) in the leaves of plant decreased with time but it was unaffected by increasing amendment. ANOVA (p < 0.05) for protein content in plant showed significant variation with the different developmental stages of the plant and statistically not significant with the different treatments. It was highest in plant grown in T5 (100%) and T4 (80%) at the maturation stages with MGDA addition. The protein content in plant increased till maturation stage. Increase in protein content with metals exposure was may be due to synthesis of new proteins like phytochelatins that combat metal stress. However, detailed investigation is needed to isolate and identify phytochelatins. Similar kind of result were reported by Qurratul et al, 2014 on the Carthamus tinctorius L. growing in fly ash amended soil. But the protein content decreased at final harvesting stage may be due to the plant ageing or due to long exposure of metalliferous soil or chelate addition. The decrease in protein content after prolonged metal exposure was may be due to increased activity of protease or other catabolic enzymes, which are activated by heavy metals and destroy proteins (Gupta and Chandra 1996).