scholarly journals Cry Protein Crystal-Immobilized Metallothioneins for Bioremediation of Heavy Metals from Water

Crystals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 287 ◽  
Author(s):  
Qian Sun ◽  
Sze Wan Cheng ◽  
Kelton Cheung ◽  
Marianne M. Lee ◽  
Michael K. Chan

Cry proteins have been the subject of intense research due to their ability to form crystals naturally in Bacillus thuringiensis (Bt). In this research we developed a new strategy that allows for the removal of cadmium and chromium from wastewater by using one Cry protein, Cry3Aa, as a framework to immobilize tandem repeats of the cyanobacterial metallothionein SmtA from Synechococcus elongatus (strain PCC 7942). SmtA is a low molecular weight cysteine-rich protein known to bind heavy metals. A series of Cry3Aa-SmtA constructs were produced by the fusion of one, three, or six tandem repeats of SmtA to Cry3Aa. Overexpression of these constructs in Bt resulted in the production of pure Cry3Aa-SmtA fusion crystals that exhibited similar size, crystallinity, and morphology to that of native Cry3Aa protein crystals. All three Cry3Aa-SmtA constructs exhibited efficient binding to cadmium and chromium, with the binding capacity correlated with increasing SmtA copy number. These results suggest the potential use of Cry3Aa-SmtA crystals as a novel biodegradable and cost-effective approach to the removal of toxic heavy metals from the environment.

Author(s):  
Enas N. Danial ◽  
Walaa A Majrashi ◽  
Ahlam O. Bin Afif ◽  
Ebtehal S Alamri ◽  
Entesar M. Alhatimi ◽  
...  

Environmental pollution of heavy metals is increasingly becoming a problem and has become of great concern due to the adverse effects it is causing around the world. These inorganic pollutants are being discarded in our waters, soils and into the atmosphere due to the rapidly growing agriculture and metal industries, improper waste disposal, fertilizers, and pesticides. Pollution in industrial areas is a serious environmental concern. Wastewater containing biotoxic substances of heavy metals in the ecosystem is one of the most important environmental and health challenges in our society. Hence, there is a growing need for the development of novel, efficient, eco-friendly, and cost-effective approach for the remediation of inorganic metals (Cr, Hg, Cd, and Pb) released into the environment and to safeguard the ecosystem. Mercury (Hg), Chromium (Cr), Cadmium (Cd), and lead (Pb) are known to cause damage to living organisms, including human beings. In this regard, recent advances in microbes-base heavy metal have propelled bioremediation as a prospective alternative to conventional techniques. Heavy metals are nonbiodegradable and could be toxic to microbes. Several microorganisms have evolved to develop detoxification mechanisms to counter the toxic effects of these inorganic metals. Several marine bacteria highly resistant and capable of growing at higher concentrations of Hg, Cr, Cd and Pb and to evaluate their potential to detoxify. Their detoxification efficiency for Hg, Cr, Cd and Pb indicates good potential for application in bioremediation of toxic heavy metals.


Processes ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 645 ◽  
Author(s):  
Mohamed A. Tahoon ◽  
Saifeldin M. Siddeeg ◽  
Norah Salem Alsaiari ◽  
Wissem Mnif ◽  
Faouzi Ben Rebah

The discharge of toxic heavy metals including zinc (Zn), nickel (Ni), lead (Pb), copper (Cu), chromium (Cr), and cadmium (Cd) in water above the permissible limits causes high threat to the surrounding environment. Because of their toxicity, heavy metals greatly affect the human health and the environment. Recently, better remediation techniques were offered using the nanotechnology and nanomaterials. The attentions were directed toward cost-effective and new fabricated nanomaterials for the application in water/wastewater remediation, such as zeolite, carbonaceous, polymer based, chitosan, ferrite, magnetic, metal oxide, bimetallic, metallic, etc. This review focused on the synthesis and capacity of various nanoadsorbent materials for the elimination of different toxic ions, with discussion of the effect of their functionalization on the adsorption capacity and separation process. Additionally, the effect of various experimental physicochemical factors on heavy metals adsorption, such as ionic strength, initial ion concentration, temperature, contact time, adsorbent dose, and pH was discussed.


2019 ◽  
Vol 47 (21) ◽  
pp. e141-e141 ◽  
Author(s):  
Antoine Daunay ◽  
Alex Duval ◽  
Laura G Baudrin ◽  
Olivier Buhard ◽  
Victor Renault ◽  
...  

Abstract Microsatellites are polymorphic short tandem repeats of 1–6 nucleotides ubiquitously present in the genome that are extensively used in living organisms as genetic markers and in oncology to detect microsatellite instability (MSI). While the standard analysis method of microsatellites is based on PCR followed by capillary electrophoresis, it generates undesirable frameshift products known as ‘stutter peaks’ caused by the polymerase slippage that can greatly complicate the analysis and interpretation of the data. Here we present an easy multiplexable approach replacing PCR that is based on low temperature isothermal amplification using recombinase polymerase amplification (LT-RPA) that drastically reduces and sometimes completely abolishes the formation of stutter artifacts, thus greatly simplifying the calling of the alleles. Using HT17, a mononucleotide DNA repeat that was previously proposed as an optimal marker to detect MSI in tumor DNA, we showed that LT-RPA improves the limit of detection of MSI compared to PCR up to four times, notably for small deletions, and simplifies the identification of the mutant alleles. It was successfully applied to clinical colorectal cancer samples and enabled detection of MSI. This easy-to-handle, rapid and cost-effective approach may deeply improve the analysis of microsatellites in several biological and clinical applications.


Author(s):  
Jianghong Liu ◽  
Jian Xue ◽  
Dandan Yuan ◽  
Xiaohang Wei ◽  
Huimin Su

Heavy metal pollution has pervaded many parts of the world, especially developing countries such as China. The discharge of wastewater containing heavy metals will cause soil pollution for a long time and harm to human health. Soil washing is an environmentally feasible and cost-effective approach for the clean-up of sites contaminated with heavy metals. As a relatively environmental protection agent, surfactants are widely used in soil washing. This paper generalized the methods of remediation of soil from heavy metals, expounded the mechanisms of soil washing by surfactant and the types of surfactants and summarized the application of different surfactants in washing heavy metals from soil. Finally, the application prospects and development trends of surfactant washing heavy metals from soil have been prospected.


Author(s):  
Girish R. Jangle

The contamination of water resources as a result of industrial activity is on the rise and is a global concern. The heavy metals found in wastewater are long lasting and non-biodegradable. Contamination with heavy metals over acceptable limits could result in major health problems. Chemical precipitation, chemical oxidation, ion exchange, membrane separation, reverse osmosis, electrodialysis, adsorption, and other technologies are used to lessen the influence of heavy metals on water bodies. Some procedures are extremely costly, energy-intensive, and frequently result in the production of harmful by-products. The use of adsorption as a cost-effective approach for removing heavy metals from industrial wastewater has been examined. The usage of Trapa bispinosa peels/shell as a low-cost adsorbent for wastewater treatment is discussed in this paper. Chemical activation was used to make activated carbons from Trapa bispinosa peels and shells. Activated carbons made from a combination of Trapa bispinosa peels/shells and Phosphoric acid with varying impregnation ratios. The results revealed that the activating temperature for the production of Trapa bispinosa-derived activated carbon is 500℃ (AC). CHNS, X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy were used to analyze the activated carbons.


2018 ◽  
Vol 1 (4) ◽  
Author(s):  
Tzung-Yuh Yeh ◽  
Chitsan Lin

Heavy metal contaminated soil due to industrial, agricultural and municipal activities is becoming a global concern. Heavy metals severely affect plants, animals and human health. A suitable technology is necessary for heavy metals removal because it cannot self-decomposition as organic compounds. Among the various technologies surveyed, phytoremediation is one of the safest, most innovative, environmental friendly and cost-effective approach for heavy metals removal. Nevertheless, traditional phytoremediation practices pose some limitations such as long processing time, unstable treatment efficiency and limited application at large scale. In many methods proposed to improve phytoremediation, integrated phytoremediation has been studied in the recent years. Integrated phytoremediation use chelating agents and phytohormones to enhance phytoremediation. This is an environmentally safe, saving time and relative high effective method. Results showed that the association of a metal ion and a chelating agent to form chelates helps to maintain the availability of metals in the soil for the uptake of plants. Phytohormones supply nutrients for the soil to support vegetable growth. Therefore, integrated phytoremediation is a promising solution to overcome the disadvantages of conventional phytoremediation. It should be taken commercialization and need more applied projects in this field to demonstrate and clarify the real potential of this technology. In view of above, this manuscript reviews the mechanism and the efficiency of integrated phytoremediation for heavy metals in contaminated soil to give an overview of this technology. 


2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Bernard E. Igiri ◽  
Stanley I. R. Okoduwa ◽  
Grace O. Idoko ◽  
Ebere P. Akabuogu ◽  
Abraham O. Adeyi ◽  
...  

The discharge of untreated tannery wastewater containing biotoxic substances of heavy metals in the ecosystem is one of the most important environmental and health challenges in our society. Hence, there is a growing need for the development of novel, efficient, eco-friendly, and cost-effective approach for the remediation of inorganic metals (Cr, Hg, Cd, and Pb) released into the environment and to safeguard the ecosystem. In this regard, recent advances in microbes-base heavy metal have propelled bioremediation as a prospective alternative to conventional techniques. Heavy metals are nonbiodegradable and could be toxic to microbes. Several microorganisms have evolved to develop detoxification mechanisms to counter the toxic effects of these inorganic metals. This present review offers a critical evaluation of bioremediation capacity of microorganisms, especially in the context of environmental protection. Furthermore, this article discussed the biosorption capacity with respect to the use of bacteria, fungi, biofilm, algae, genetically engineered microbes, and immobilized microbial cell for the removal of heavy metals. The use of biofilm has showed synergetic effects with many fold increase in the removal of heavy metals as sustainable environmental technology in the near future.


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