Extracellular Electron Transfer by Shewanella oneidensis Controls Palladium Nanoparticle Phenotype

Abstract

Biological production of inorganic materials is impeded by relatively few organisms possessing genetic and metabolic linkage to material properties. The physiology of electroactive bacteria is intimately tied to inorganic transformations, which makes genetically tractable and well-studied electrogens, such as Shewanella oneidensis, attractive hosts for material synthesis. Notably, this species is capable of reducing a variety of transition-metal ions into functional nanoparticles, but exact mechanisms of nanoparticle biosynthesis remain ill-defined. We report two key factors of extracellular electron transfer by S. oneidensis, the outer membrane cytochrome, MtrC, and soluble redox shuttles (flavins), that affect Pd nanoparticle formation. Changes in the expression and availability of these electron transfer components drastically modulated particle phenotype, including particle synthesis rate, structure, and cellular localization. These relationships may serve as the basis for biologically tailoring Pd nanoparticle catalysts and could potentially be used to direct the biogenesis of other metal nanomaterials.

Shotgun proteomics analysis of nanoparticle-synthesisingDesulfovibrio alaskensisin response to platinum and palladium

“…This leads to an increased deposition rates and, in turn, an increased localised turnover rate of the platinum ions by the autocatalytic abilities of the platinum nanoparticles thus leading overall to larger nanoparticles. This supports previous work which concluded that the NiFe hydrogenase is required for nanoparticle synthesis in Desulfovibrio (18) and also their deposition on the outer membranes in Shewanella (20). Samples of nanoparticles produced by Desulfovibrio transformed with either pMO-2137 or the empty vctor control were analysed using EDS (Energy-dispersive spectroscopy).…”

“…The NiFe hydrogenases of D. fructosovorans have been shown to be involved in technetium reduction (17). They similarly have a role, along with a Fe-containing hydrogenase, in Pd(0) deposition and clustering in both the periplasm (18) and on cellular membranes (19), while more recently have been implicated in having a roll in palladium deposition in Shewanella (20). While important for the anaerobic reduction of palladium by Desulfovibrio sp., they are not required for the aerobic reduction of palladium by E. coli (21).…”

Shewanella oneidensis Assisted Biosynthesis of Pd/Reductive‐Graphene‐Oxide Nanocomposites for Oxygen Reduction Reaction

“…[30] Two key factors of extracellular electron transfer by S. oneidensis, the outer membrane cytochrome, and soluble redox shuttles, that affect Pd nanoparticle formation. [31] It is worth mentioning that the addition of GO significantly increases the recovery rate of Pd in the product. We studied TEM was utilized to visually demonstrate the typical Pd nanoparticles that were decorated on the bacteria cells and rGO sheets in Bio-Pd and Bio-Pd/rGO.…”

“…It was suggested that S. oneidensis MR‐1 has a large number of terminal reductases, which is implicated in electron transfer for the reduction reaction . Two key factors of extracellular electron transfer by S. oneidensis , the outer membrane cytochrome, and soluble redox shuttles, that affect Pd nanoparticle formation …”

Combinatorial design of chemical‐dependent protein switches for controlling intracellular electron transfer

“…While hybrid cells and materials have been reported that leverage synthetic biology for in situ sensing and chemical synthesis, these studies typically control ET at the transcriptional level, limiting the speed (minutes to hours) at which ET can be regulated for different applications . Overcoming this timescale challenge will enable increased temporal resolution for in situ sensing applications and precision control over ET during chemical and material synthesis . One way to improve the speed at which ET is regulated for these diverse applications is to develop chemical‐induced proteins that control ET through post‐translational mechanisms that operate on faster timescales (seconds to minutes) …”