title: Bio-recovery of non-essential heavy metals by intra- and extracellular mechanisms in free-living microorganisms.
abstract: Free-living microorganisms may become suitable models for recovery of non-essential and essential heavy metals from wastewater bodies and soils by using and enhancing their accumulating and/or leaching abilities. This review analyzes the variety of different mechanisms developed mainly in bacteria, protists and microalgae to accumulate heavy metals, being the most relevant those involving phytochelatin and metallothionein biosyntheses; phosphate/polyphosphate metabolism; compartmentalization of heavy metal-complexes into vacuoles, chloroplasts and mitochondria; and secretion of malate and other organic acids. Cyanide biosynthesis for extra-cellular heavy metal bioleaching is also examined. These metabolic/cellular processes are herein analyzed at the transcriptional, kinetic and metabolic levels to provide mechanistic basis for developing genetically engineered microorganisms with greater capacities and efficiencies for heavy metal recovery, recycling of heavy metals, biosensing of metal ions, and engineering of metalloenzymes.
authors.affiliation: Departamento de Bioquímica, Instituto Nacional de Cardiología "Ignacio Chávez", México D.F. 14080, México. Electronic address: jorge.garcia@cardiologia.org.mx.
authors.forename: Jorge D
authors.initials: JD
authors.lastname: García-García
authors.affiliation: Departamento de Bioquímica, Instituto Nacional de Cardiología "Ignacio Chávez", México D.F. 14080, México.
authors.forename: Rosina
authors.initials: R
authors.lastname: Sánchez-Thomas
authors.affiliation: Departamento de Bioquímica, Instituto Nacional de Cardiología "Ignacio Chávez", México D.F. 14080, México.
authors.forename: Rafael
authors.initials: R
authors.lastname: Moreno-Sánchez
mesh_terms: D001419:Bacteria / Q000737:chemistry / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D001673:Biodegradation, Environmental; D005110:Extracellular Space / Q000737:chemistry / Q000378:metabolism; D042541:Intracellular Space / Q000737:chemistry / Q000378:metabolism; D019216:Metals, Heavy / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D019216:Metals, Heavy
keywords: Bioleaching; Cadmium; Cyanide biosynthesis; Cyanogenic bacteria; Euglena gracilis; Free-living microorganisms; Gold; Heavy metal bioaccumulation; Phytochelatin metabolism; Recovery of heavy metals