TY - JOUR

T1 - Heavy metal removal by bioaccumulation using genetically engineered microorganisms

AU - Diep, Patrick

AU - Mahadevan, Radhakrishnan

AU - Yakunin, Alexander

N1 - This work was supported by the Ontario Ministry of Economic Development, Job Creation and Trade through the Elements of Bio-mining ORF-RE program. PD is grateful to be a recipient of the Ontario Graduate Scholarship

PY - 2018/10/29

Y1 - 2018/10/29

N2 - Wastewater effluents from mines and metal refineries are often contaminated with heavy metal ions, so they pose hazards to human and environmental health. Conventional technologies to remove heavy metal ions are well-established, but the most popular methods have drawbacks: chemical precipitation generates sludge waste, and activated carbon and ion exchange resins are made from unsustainable non-renewable resources. Using microbial biomass as the platform for heavy metal ion removal is an alternative method. Specifically, bioaccumulation is a natural biological phenomenon where microorganisms use proteins to uptake and sequester metal ions in the intracellular space to utilize in cellular processes (e.g. enzyme catalysis, signaling, stabilizing charges on biomolecules). Recombinant expression of these import-storage systems in genetically engineered microorganisms allows for enhanced uptake and sequestration of heavy metal ions. This has been studied for over two decades for bioremediativeapplications, but successful translation to industrial-scale processes is virtually non-existent. Meanwhile, demands for metalresources are increasing while discovery rates to supply primary grade ores are not. This review re-thinks how bioaccumulationcan be used and proposes that it can be developed for bioextractive applications – the removal and recovery of heavy metal ionsfor downstream purification and refining, rather than disposal. This review consolidates previously tested import-storagesystems into a biochemical framework and highlights efforts to overcome obstacles that limit industrial feasibility, therebyidentifying gaps in knowledge and potential avenues of research in bioaccumulation.

AB - Wastewater effluents from mines and metal refineries are often contaminated with heavy metal ions, so they pose hazards to human and environmental health. Conventional technologies to remove heavy metal ions are well-established, but the most popular methods have drawbacks: chemical precipitation generates sludge waste, and activated carbon and ion exchange resins are made from unsustainable non-renewable resources. Using microbial biomass as the platform for heavy metal ion removal is an alternative method. Specifically, bioaccumulation is a natural biological phenomenon where microorganisms use proteins to uptake and sequester metal ions in the intracellular space to utilize in cellular processes (e.g. enzyme catalysis, signaling, stabilizing charges on biomolecules). Recombinant expression of these import-storage systems in genetically engineered microorganisms allows for enhanced uptake and sequestration of heavy metal ions. This has been studied for over two decades for bioremediativeapplications, but successful translation to industrial-scale processes is virtually non-existent. Meanwhile, demands for metalresources are increasing while discovery rates to supply primary grade ores are not. This review re-thinks how bioaccumulationcan be used and proposes that it can be developed for bioextractive applications – the removal and recovery of heavy metal ionsfor downstream purification and refining, rather than disposal. This review consolidates previously tested import-storagesystems into a biochemical framework and highlights efforts to overcome obstacles that limit industrial feasibility, therebyidentifying gaps in knowledge and potential avenues of research in bioaccumulation.

U2 - 10.3389/fbioe.2018.00157

DO - 10.3389/fbioe.2018.00157

M3 - Article

VL - 6

JO - Frontiers in Bioengineering and Biotechnology

JF - Frontiers in Bioengineering and Biotechnology

M1 - 157

ER -