title: Scale-up of the production of highly reactive biogenic magnetite nanoparticles using Geobacter sulfurreducens.
abstract: Although there are numerous examples of large-scale commercial microbial synthesis routes for organic bioproducts, few studies have addressed the obvious potential for microbial systems to produce inorganic functional biomaterials at scale. Here we address this by focusing on the production of nanoscale biomagnetite particles by the Fe(III)-reducing bacterium Geobacter sulfurreducens, which was scaled up successfully from laboratory- to pilot plant-scale production, while maintaining the surface reactivity and magnetic properties which make this material well suited to commercial exploitation. At the largest scale tested, the bacterium was grown in a 50 l bioreactor, harvested and then inoculated into a buffer solution containing Fe(III)-oxyhydroxide and an electron donor and mediator, which promoted the formation of magnetite in under 24 h. This procedure was capable of producing up to 120 g of biomagnetite. The particle size distribution was maintained between 10 and 15 nm during scale-up of this second step from 10 ml to 10 l, with conserved magnetic properties and surface reactivity; the latter demonstrated by the reduction of Cr(VI). The process presented provides an environmentally benign route to magnetite production and serves as an alternative to harsher synthetic techniques, with the clear potential to be used to produce kilogram to tonne quantities.
authors.affiliation: School of Earth, Atmospheric and Environmental Sciences, and Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester M13 9PL, UK Geomicrobiology, Center for Applied Geoscience, University of Tuebingen, Sigwartstrasse 10, 72076 Tuebingen, Germany.
authors.forename: J M
authors.initials: JM
authors.lastname: Byrne
authors.affiliation: School of Earth, Atmospheric and Environmental Sciences, and Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester M13 9PL, UK Manchester Institute of Biotechnology, University of Manchester, Manchester M1 7DN, UK.
authors.forename: H
authors.initials: H
authors.lastname: Muhamadali
authors.affiliation: School of Earth, Atmospheric and Environmental Sciences, and Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester M13 9PL, UK.
authors.forename: V S
authors.initials: VS
authors.lastname: Coker
authors.affiliation: The Centre for Process Innovation, CPI, Wilton Centre, Wilton, Redcar TS10 4RF, UK.
authors.forename: J
authors.initials: J
authors.lastname: Cooper
authors.affiliation: School of Earth, Atmospheric and Environmental Sciences, and Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester M13 9PL, UK jon.lloyd@manchester.ac.uk.
authors.forename: J R
authors.initials: JR
authors.lastname: Lloyd
mesh_terms: D045302:Geobacter / Q000737:chemistry* / Q000378:metabolism*; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction
chemical_list: D058185:Magnetite Nanoparticles
keywords: Fe(III) reduction; bioreactor; geobiology; nanotechnology; remediation