Trends in Biotechnology
Volume 37, Issue 11, November 2019, Pages 1255-1268
Journal home page for Trends in Biotechnology

Review
New Prospects for Modified Algae in Heavy Metal Adsorption

https://doi.org/10.1016/j.tibtech.2019.04.007Get rights and content

Highlights

  • Novel finely tuned algae can improve the selectivity and performance of heavy metal adsorption.

  • Molecular modification can be used to display metal-binding proteins at the cell surface via gene overexpression or by introducing exogenous DNA to generate transgenic algae.

  • The performance of chemical modification has been highly variable, and more studies will be necessary to overcome its limitations.

  • The extraction approach is promising because of the strong metal-binding properties of algae that have been attributed to alginate.

  • Algae-based nanoparticles show better performance in heavy metal removal compared with raw algae.

Heavy metal pollution is one of the most pervasive environmental problems globally. Novel finely tuned algae have been proposed as a means to improve the efficacy and selectivity of heavy metal biosorption. This article reviews current research on selective algal heavy metal adsorption and critically discusses the performance of novel biosorbents. We emphasize emerging state-of-the-art techniques that customize algae for enhanced performance and selectivity, particularly molecular and chemical extraction techniques as well as nanoparticle (NP) synthesis approaches. The mechanisms and processes for developing novel algal biosorbents are also presented. Finally, we discuss the applications, challenges, and future prospects for modified algae in heavy metal biosorption.

Section snippets

Heavy Metals: Pollution, Health Effects, and Remediation

Heavy metal pollution poses serious health risks to living organisms and leads to deterioration of environmental quality as a result of the high toxicity of heavy metals (see Glossary) combined with their nonbiodegradability and ability to bioaccumulate in living organisms and the food chain. Various industries directly or indirectly release heavy metals in liquid waste effluent into rivers or the sea, which has resulted in increasing public concern. In light of this issue, the World Health

Biological and Molecular Approaches

Genetic engineering has recently become a subject of close scrutiny in the field because it allows algae to be fine-tuned to improve their selectivity and adsorption capacity. Algal genetic engineering has been explored since the end of the 1970s in the model system of the cyanobacterium (blue-green alga) Synechococcus sp. 7002, which was transformed by introducing exogenous homologous DNA carrying a selectable marker.

The exceptional tolerance of algae to elevated heavy metal concentrations has

Chemical Approaches

In the biosorption process, the algal cell wall is the first barrier encountered by heavy metals, and the constituents of the cell wall determine the mechanism of heavy metal sequestration. For example, a typical algal cell wall consists of a cellulose skeleton in the form of xylans or mannans as well as an amorphous embedding matrix that is typically composed of alginate, alginic acid, and sulfated galactans. The functional groups of polysaccharides and lipids that contribute to the adsorption

Alginate Extraction Approach

The role of alginate in adsorption has been demonstrated by Bertagnolli and colleagues [49] who reported a 36.1% decrease in Cr(VI) adsorption capacity after alginate has been extracted from Sargassum filipendula. Although alginate is deemed to be the main component responsible for algal heavy metal binding, it is also an important resource for food, textile, and pharmaceutical products. Nevertheless, alginate extraction residues may still have metal-binding properties because of the remaining

Nanoparticle Synthesis Approach

One emerging technique in algal heavy metal adsorption is the synthesis of NPs from algal biomass. The field of NP synthesis is growing rapidly, fueled by breakthroughs in different synthesis mechanisms and the prospect of unique applications owing to their outstanding properties. These fascinating properties of NPs are due to their small sizes, and thus a high surface area to volume ratio, and superior reactivity versus their bulk counterparts [53]. Synthesis of metal NPs mediated by algae is

Future Challenges and Opportunities

The aforementioned approaches to enhance algal heavy metal adsorption capacity and selectivity have inherent prospects and bottlenecks. Algae show extraordinary potential for metal biosorption owing to their abundance and programmable photoautotrophy for genetic design and construction [26]. Genetic engineering by expressing metalloregulatory proteins can be applied to selectively adsorb heavy metals because different types of proteins differ in their affinities for specific heavy metals. In

Concluding Remarks

This comprehensive review presents an updated account of emerging approaches to enhance algal heavy metal biosorption capacity and selectivity. Biological modifications have created a paradigm shift in algal biosorption because they allow the algae to be designed to express specific binding proteins at their surfaces to adsorb targeted metal species. However, compared with other microorganisms such as bacteria and yeast, genetic engineering of algae is still in its infancy, and there is a need

Acknowledgements

Our research is supported by the Malaysia Ministry of Education (TR001A-2015A) and the University of Malaya (RP025B-SUS18). The authors gratefully acknowledge the financial support received from Taiwan’s Ministry of Science and Technology (MOST) under grant numbers 108-3116-F-006-007-CC1, 107-2221-E-006-112-MY3, and 107-2621-M-006-003.

Glossary

Alginate extract
an alginate salt extract of algae, usually in the form of soluble sodium alginate or the precipitate of sodium alginate solution either from alginic acid or calcium alginate.
Alginate extract residue
algal cell biomass produced in the alginate extraction process. After alginate extraction, the biomass contains many of the constituents of the raw algae, and thus has potential for heavy metal adsorption.
Biochar
carbonized biomass obtained from biological resources.
Biosorption
a

References (80)

  • H.V. Perales-Vela

    Heavy metal detoxification in eukaryotic microalgae

    Chemosphere

    (2006)
  • E. Torricelli

    Cadmium tolerance, cysteine and thiol peptide levels in wild type and chromium-tolerant strains of Scenedesmus acutus (Chlorophyceae)

    Aquat. Toxicol.

    (2004)
  • A. Ibuot

    Metal bioremediation by CrMTP4 over-expressing Chlamydomonas reinhardtii in comparison to natural wastewater-tolerant microalgae strains

    Algal Res.

    (2017)
  • S. Hu

    Cadmium sequestration in Chlamydomonas reinhardtii

    Plant Sci.

    (2001)
  • S. Qin

    Advances in genetic engineering of marine algae

    Biotechnol. Adv.

    (2012)
  • Z. He

    Removal of mercury from sediment by ultrasound combined with biomass (transgenic Chlamydomonas reinhardtii)

    Chemosphere

    (2011)
  • F. Yang

    Preparation and characterization of chitosan encapsulated Sargassum sp. biosorbent for nickel ions sorption

    Bioresour. Technol.

    (2011)
  • Y. Mata

    Biosorption of cadmium, lead and copper with calcium alginate xerogels and immobilized Fucus vesiculosus

    J. Hazard. Mater.

    (2009)
  • M.R. Fagundes-Klen

    Equilibrium study of the binary mixture of cadmium–zinc ions biosorption by the Sargassum filipendula species using adsorption isotherms models and neural network

    Biochem. Eng. J.

    (2007)
  • V.K. Gupta

    Biosorption of nickel onto treated alga (Oedogonium hatei): application of isotherm and kinetic models

    J. Colloid Interface Sci.

    (2010)
  • C. Yacou

    Chemical structure investigation of tropical Turbinaria turbinata seaweeds and its derived carbon sorbents applied for the removal of hexavalent chromium in water

    Algal Res.

    (2018)
  • I.W. Mwangi et al.

    Removal of heavy metals from contaminated water using ethylenediamine-modified green seaweed (Caulerpa serrulata)

    Phys. Chem. Earth A/B/C

    (2012)
  • L. Yang et al.

    Biosorption of hexavalent chromium onto raw and chemically modified Sargassum sp

    Bioresour. Technol.

    (2008)
  • X. Li

    Novel magnetic beads based on sodium alginate gel crosslinked by zirconium (IV) and their effective removal for Pb2+ in aqueous solutions by using a batch and continuous systems

    Bioresour. Technol.

    (2013)
  • E-B. Son

    Heavy metal removal from aqueous solutions using engineered magnetic biochars derived from waste marine macro-algal biomass

    Sci. Total Environ.

    (2018)
  • E-B. Son

    A novel approach to developing a reusable marine macro-algae adsorbent with chitosan and ferric oxide for simultaneous efficient heavy metal removal and easy magnetic separation

    Bioresour. Technol.

    (2018)
  • H. Demey

    A novel algal-based sorbent for heavy metal removal

    Chem. Eng. J.

    (2018)
  • C. Bertagnolli

    Chromium biosorption using the residue of alginate extraction from Sargassum filipendula

    Chem. Eng. J.

    (2014)
  • S.L. Cardoso

    Biosorption of toxic metals using the alginate extraction residue from the brown algae Sargassum filipendula as a natural ion-exchanger

    J. Clean. Prod.

    (2017)
  • S.K. Papageorgiou

    Heavy metal sorption by calcium alginate beads from Laminaria digitata

    J. Hazard. Mater.

    (2006)
  • S.R. Vijayan

    Seaweeds: a resource for marine bionanotechnology

    Enzym. Microb. Technol.

    (2016)
  • G.L. Dotto

    Biosorption of food dyes onto Spirulina platensis nanoparticles: equilibrium isotherm and thermodynamic analysis

    Bioresour. Technol.

    (2012)
  • G.L. Dotto

    Preparation of bionanoparticles derived from Spirulina platensis and its application for Cr (VI) removal from aqueous solutions

    J. Ind. Eng. Chem.

    (2012)
  • C. Wan

    Current progress and future prospect of microalgal biomass harvest using various flocculation technologies

    Bioresour. Technol.

    (2015)
  • X. Liu

    Human health risk assessment of heavy metals in soil–vegetable system: a multi-medium analysis

    Sci. Total Environ.

    (2013)
  • W-W. Tang

    Impact of humic/fulvic acid on the removal of heavy metals from aqueous solutions using nanomaterials: a review

    Sci. Total Environ.

    (2014)
  • G.S. Simate

    Coal-based adsorbents for water and wastewater treatment

    J. Environ. Chem. Eng.

    (2016)
  • H. Itoh

    Dietary cadmium intake and breast cancer risk in Japanese women: a case–control study

    Int. J. Hyg. Environ. Health

    (2014)
  • C. Borba

    Removal of nickel (II) ions from aqueous solution by biosorption in a fixed bed column: experimental and theoretical breakthrough curves

    Biochem. Eng. J.

    (2006)
  • M. Naushad

    Nickel ferrite bearing nitrogen-doped mesoporous carbon as efficient adsorbent for the removal of highly toxic metal ion from aqueous medium

    Chem. Eng. J.

    (2017)
  • Cited by (241)

    View all citing articles on Scopus
    View full text