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EPSRC (EP/I007806/1; EP/D05768X/1), BBSRC (BB/ C516128/1), NERC (NE/L014076/1), The Royal Society (Industrial Fellowship) and Spanish Government Sistema Nacional de Garantia Juvenil grant PEJ-2014-P-00391., This work was supported by EPSRC (grants No EP/ I007806/1 and EP/D05768X/1), BBSRC (grant No BB/ C516128/1), NERC (grant NE/L014076/1) and by a Royal Society Industrial Fellowship to LEM for secondment into C-Tech Innovation Ltd., who provided the bespoke apparatus used in this work. We acknowledge the invaluable contributions of the late Dr Ruth Wroe of C-Tech Innovation Ltd. into useful discussions and the kind permission of Drs S. Megit, C. Berry and A. Morby (University of Cardiff, UK) to show their unpublished work in Supplementary Information. This work was partially supported by the Spanish Government Sistema Nacional de Garantia Juvenil Grant PEJ-2014-P- 00391 (Promocion de Empleo Joven e Implantacion de la Garantia Juvenil 2014, MINECO) with a scholarship to JGB. We also thank the EM Centre at U. Granada for access to high-resolution electron microscopy (in Fig. S2 and S3). All authors declare no competing interests., Desulfovibrio desulfuricans reduces Pd(II) to Pd(0)-nanoparticles (Pd-NPs) which are catalytically active in 2-pentyne hydrogenation. To make Pd-NPs, resting cells are challenged with Pd(II) ions (uptake), followed by addition of electron donor to promote bioreduction of cell-bound Pd(II) to Pd(0) (bio-Pd). Application of radiofrequency (RF) radiation to prepared 5 wt% bio-Pd catalyst (60 W power, 60 min) increased the hydrogenation rate by 70% with no adverse impact on selectivity to cis-2-pentene. Such treatment of a 5 wt% Pd/carbon commercial catalyst did not affect the conversion rate but reduced the selectivity. Lower-dose RF radiation (2-8 W power, 20 min) was applied to the bacteria at various stages before and during synthesis of the bio-scaffolded Pd-NPs. The reaction rate (mu mol 2-pentyne converted s(-1)) was increased by similar to threefold by treatment during bacterial catalyst synthesis. Application of RF radiation (2 or 4 W power) to resting cells prior to Pd(II) exposure affected the catalyst made subsequently, increasing the reaction rate by 50% as compared to untreated cells, while nearly doubling selectivity for cis 2-pentene. The results are discussed with respect to published and related work which shows altered dispersion of the Pd-NPs made following or during RF exposure., UK Research & Innovation (UKRI) Engineering & Physical Sciences Research Council (EPSRC) EP/I007806/1 EP/D05768X/1, UK Research & Innovation (UKRI) Biotechnology and Biological Sciences Research Council (BBSRC) BB/C516128/1, UK Research & Innovation (UKRI), Natural Environment Research Council (NERC) NE/L014076/1, Royal Society of London European Commission, Spanish Government Sistema Nacional de Garantia Juvenil grant PEJ-2014-P-00391

Hydrogen, an emergent alternative energy vector to fossil fuels, can be produced sustainably by fermentation of cellulose following hydrolysis. Fermentation feedstock was produced hydrolytically using hot compressed water. The addition of CO2 enhanced hydrolysis by ~26% between 240 and 260 C with comparable hydrolysis products as obtained under N2 but at a 10 C lower temperature. Co-production of inhibitory 5-hydromethyl furfural was mitigated via activated carbon sorption, facilitating fermentative biohydrogen production from the hydrolysate by Escherichia coli. Post-fermentation E. coli cells were recycled to biomanufacture supported Pd/Ru nanocatalyst to up-convert liquid-extracted 5-HMF to 2,5-dimethyl furan, a precursor of ‘drop in’ liquid fuel, in a one-pot reaction. This side stream up-valorisation mitigates against the high ‘parasitic’ energy demand of cellulose bioenergy, potentially increasing process viability via the coupled generation of two biofuels. This is discussed with respect to example data obtained via a hydrogen biotechnology with catalytic side stream up-conversion from cellulose feedstock., UK Research & Innovation (UKRI), Engineering & Physical Sciences Research Council (EPSRC) EP/D05768X/1 EP/E034888/1, Biotechnology and Biological Sciences Research Council (BBSRC) BB/C516195/2 BB/E003788/1, Natural Environment Research Council (NERC) NE/L014076/1, Royal Society of London, European Commission, Government of Mexico 203186, Spanish Government Sistema Nacional de Garantia Juvenil grant (Promocion de Empleo Joven e Implantacion de la Garantia Juvenil 2014, MINECO) PEJ-2014-P-00391, General Electric POC46

The ability to clearly relate local structure to function is desirable for many catalytically relevant Pd-containing systems. This report represents the first direct 105Pd solid state NMR measurements of diamagnetic inorganic (K2Pd(IV)Cl6, (NH4)2Pd(IV)Cl6 and K2Pd(IV)Br6) complexes, and micron- and nano-sized Pd metal particles at room temperature, thereby introducing effective 105Pd chemical shift and Knight shift ranges in the solid state. The very large 105Pd quadrupole moment (Q) makes the quadrupole parameters (CQ, ηQ) extremely sensitive to small structural distortions. Despite the well-defined high symmetry octahedral positions describing the immediate Pd coordination environment, 105Pd NMR measurements can detect longer range disorder and anisotropic motion in the interstitial positions. The approach adopted here combines high resolution X-ray pair distribution function (PDF) analyses with 105Pd, 39K and 35Cl MAS NMR, and shows solid state NMR to be a very sensitive probe of short range structural perturbations. Solid state 105Pd NMR observations of ∼44–149 μm Pd sponge, ∼20–150 nm Pd black nanoparticles, highly monodisperse 16 ± 3 nm PVP-stabilised Pd nanoparticles, and highly polydisperse ∼2–1100 nm biomineralized Pd nanoparticles (bio-Pd) on pyrolysed amorphous carbon detect physical differences between these systems based on relative bulk:surface ratios and monodispersity/size homogeneity. This introduces the possibility of utilizing solid state NMR to help elucidate the structure–function properties of commercial Pd-based catalyst systems.\ud \ud

With the aim to recover precious metals (PMs) from spent automotive catalyst leachates into new catalysts, cells of Escherichia coli first reduced Pd(II) or Pt(IV) physiologically to nanoparticulate cell-bound Pd(0) and Pt(0). Metallised cells were then used as chemical catalysts for the reductive recovery of precious metals from model solutions and from aqua regia leachates of crushed spent automotive catalyst. Metal removal, which was slower from real leachate due to interference by other contaminants, was complete after 60 h. Biofabricated PM catalyst from waste reduced 0.5 mM Cr(VI) to a similar extent to commercial 5% Pd catalyst but at ∼half the rate. The hydrogenation of 2-pentyne was examined using commercial Pd on Al2O3 catalyst and biofabricated Pd/Pt catalyst, the latter showing more than 3-fold enhanced selectivity towards the desired cis-pentene product. Hence, biorefined PMs offer a clean route to waste treatment and effective neo-catalyst biomanufacture.

For new technologies to become market competitors, they must operate substantially cheaper than their competitors or achieve outcomes that are difficult by current methods. Classical life cycle analysis (LCA) focuses on salient ecological impacts but bypasses key economic aspects and does not assign quantifiable benefits. This chapter factors in the benefits of environmental protection, reduced CO2 emissions, and the environmental impacts of oil extraction and fuel production using a well-to-gate (also known as cradle-to-gate) LCA, as well as the economics involving the mitigation of landfill gate fees for waste resources and social cost of carbon. The case histories evaluated involve catalysts bio-refined from wastes for application in cleaner extraction, upgrading, and processing of heavy fossil and pyrolysis bio-oils and comparisons to their commercial counterparts. Each case history material was analysed with a commercial catalyst and a bio-catalyst assessed as an alternative based on oil ratios (%eq. of g : g). Pyrolysis bio-oils from waste wood and algal sources were found to be upgradable successfully using both catalysts. They produce carbon-neutral fuels because of carbon sequestration during photosynthetic biomass growth, and the bacterial components supporting the catalyst become assimilated into the fuel.

Functional nanomaterials are employed in a wide range of technological and industrial applications and searches for new and unique particles and production methods are expanding. Microbes now serve as widely available and untapped biotechnological resources due to their abilities to precipitate nanomaterials in systems utilising waste products and process streams as raw materials. Of particular appeal is the potential to offer a green biosynthesis approach to nanomaterial production (compared to traditional processing methods) for precious metal (palladium and gold) nanocatalysts, copper, selenium, tellurium and sulphur-based semi-conductors and quantum dots and magnetic iron-based nanomaterials. This chapter will focus on Fe and precious metal bionanomaterials, along with magnetic nanomaterials, catalysts and quantum dots. It will cover new opportunities built around tandem materials where synthetic biological approaches can be used to extend functionality by co-expressing bionanomaterials and enzymes (e.g. biocatalysts). Wherever possible, the potential use of waste substrates to add financial and economic incentives to drive product development within a circular economy is emphasised.

We acknowledge the support of NERC (Grant No NE/L014076/1) in the research presented here (AJM and RLO) to develop ZnS-based quantum dots technology via resource recovery from waste. The underpinning evaluation of commercial quantum dots in the three test photobiological systems was supported by the Discipline Hopping Award scheme co-funded by EPSRC, BBSRC, and MRC. The support of BBSRC is acknowledged for MRes studentships (AG and FW).

Aerobically grown E. coli cells reduced Pd(II) via a novel mechanism using formate as the electron donor. This reduction was monitored in real-time using extended X-ray absorption fine structure. Transmission electron microscopy analysis showed that Pd(0) nanoparticles, confirmed by X-ray diffraction, were precipitated outside the cells. The rate of Pd(II) reduction by E. coli mutants deficient in a range of oxidoreductases was measured, suggesting a molybdoprotein-mediated mechanism, distinct from the hydrogenase-mediated Pd(II) reduction previously described for anaerobically grown E. coli cultures. The potential implications for Pd(II) recovery and bioPd catalyst fabrication are discussed.

The oil industry increasingly exploits ‘heavy oils’ which are highly viscous and difficult to extract in a ‘clean’ way. Heat and ‘cracking’ catalysts facilitate extraction e.g. by applying the ‘Toe-to-Heel Air Injection’ (THAI) and ‘Catalytic Process In-Situ’ (CAPRI) techniques. Cracking catalysts include palladium. Use of Pd-catalyst is uneconomic but by using palladium deposited on bacterial cells (in combination with other PMs) a waste can be turned into a valuable product. Road dusts contain precious metals (PMs) which arise from automotive catalytic converters. Once washed from roads the PMs are dispersed to the environment. Model r oad dust solutions were produced to simulate acid leaching of road dust to solubilise the PMs. Bacteria cannot directly recover PMs from acidic leachate but by lightly depositing Pd(0) ‘seeds’ enzymatically the resulting ‘bio-Pd’-catalyst accumulates PMs from waste model leachate. The bio-catalyst was assessed in the reduction of heavy oil viscosity compared to a commercial catalyst, achieving this reduction with significantly less coke formation, which was not attributable to the biomass component alone.

Rare earth elements (REEs) are highly valuable due to the complex nature of their extraction from primary and secondary sources. A key feature is that REEs often co-occur with uranium and thorium which, being radioactive, increase the hazard and complexity of REE recovery. A bioprocess which utilizes enzymatically-generated inorganic phosphate to precipitate REEs from solution as their phosphate biominerals is highly effective in the recovery of REEs, effecting rapid recovery onto immobilized bacterial biofilm at high flow-through rates. This also bioprecipitates U and Th. The metal recovery process requires addition of an organic phosphate substrate, e.g. glycerol 2-phosphate (G2P), the cleavage of which provides the inorganic phosphate source for REE biomineralization. G2P is expensive, precluding its large scale use, but early work using uranium showed that tributyl phosphate (TBP) can be used as an alternative phosphate donor molecule. The potential for substitution of G2P by TBP for biorecovery of neodymium is described and a new approach is proposed for enhancing the metal selectivity for REEs against uranium.

A Serratia sp. expresses a high level of acid phosphatase when grown continuously under carbon limitation. In the presence of CaCl2, biosynthesis of nanocrystalline hydroxyapatite (bio-HA) was achieved by utilizing phosphate released via enzymatic cleavage of an applied substrate (glycerol 2-phosphate: G2P). Hydroxyapatite crystals were identified by energy dispersive X-ray emission (EDX) and selected area diffraction (SAD). X-ray powder diffraction (XRD) analysis gave a mean crystallite size of ∼21–32 nm, with the smallest crystals (21–24 nm) obtained using 1 mM Ca2+ and 1 mM G2P. The uptake of Eu3+ and Sr2+ by bio-HA made by continuously pregrown cells (0.42 mg/mg and 0.043 mg/mg respectively) was ∼20% greater for Sr2+ than was previously reported for bio-HA material of size ∼40 nm made by batch-pregrown cells, while the corresponding uptake of Eu3+ was increased by > 1.8-fold. This was attributed to the localization of Eu (III) at grain boundaries by reference to previous work and highlights th...

A novel method for simultaneous reduction of graphene oxide (GO) and palladium salt, Pd(II), using Escherichia coli (E. coli) in the separate presence of two different mild reducing agents (hydrogen and formate) is investigated to successfully produce reduced GO (rGO)-biomass/Pd hybrid material for potential use as an electrocatalyst. Transmission electron microscopy, X-ray diffraction, thermo-gravimetric analysis, X-ray photoelectron spectroscopy and Raman microscopy demonstrate the successful reduction of Pd(II), GO and the biomass, resulting in the formation of Pd nanoparticles (PdNPs) on an rGO–biomass hybrid. The distribution of the NPs was found to be dependent on the type of reducing agent. PdNPs formed on rGO sheets showed relatively uniform distribution and size control (2–5 nm), whereas PdNPs on the bacterial scaffold were larger (up to 10 nm in size). Raman spectroscopy studies suggest that the presence of Pd leads to oxygen reduction and increased crystallinity in the bacterial biomass. Previous studies have suggested the potential for a bacterially-supported Pd electrocatalyst in fuel cells and, independently, the suitability of rGO as a support for PdNPs. This study confirms the simultaneous bacterial reduction of Pd(II) and GO and the association between the bacterial cells and rGO. We suggest that the simultaneous presence of E. coli and mild reducing agent together with GO and Pd(II) creates an interactive and synergistic environment in a hybrid material to allow (a) better control of PdNP size and distribution both on the inside of the bacterial membrane and on the rGO sheets and (b) increased crystallinity of the bacterial biomass compared to systems with bacteria alone.

Batch-grown cells and a continuously-grown biofilm of a Serratia sp. were utilized to recover the rare earth elements (REEs) lanthanum and neodymium from solution. Selectivity was obtained for La(III) over Th(IV) using columns of polyacrylamide gel-immobilized cells challenged at a rapid flow rate, exploiting the different solution chemistries and behaviors of REEs(III) and Th(IV). Biofilm-grown cells had a ten-fold higher activity of mediating phosphatase, which promotes metal deposition as the corresponding metal phosphate, reflected as a correspondingly enhanced level of removal of Nd(III) (as NdPO4) in flow-through columns utilizing the biofilm on reticulated foam. The biofilms retained activity in the removal of Nd(III) for >1 year, losing activity exponentially with a half life of 3 months. The flow rate giving 50% removal (FA1/2) of Nd(III) by 3 month old biofilms at pH 5.5 was 272 and 275 mL h−1 using two independent biofilm preparations, equivalent to a FA1/2 of 34 column volumes per h for fresh biofilms. The removal of Nd(III) was sustained at pH values down to 3.5 with approx. 20% of the column activity lost upon return to pH 5.5. A similar result occurred in the presence of the common REE leaching agent ammonium sulfate (100 mM), but this did not affect the ability of Serratia sp. to recover REEs. With a view to the potential for future biomanufacturing of Nd(III)-catalysts, the deposited material was identified as NdPO4 by X-ray powder diffraction with a nanoparticle size of 14.5 nm, irrespective of the biofilm age.

Summary Microbially generated or supported nanocatalysts have potential applications in green chemistry and environmental application. However, precious (and base) metals biorefined from wastes may be useful for making cheap, low‐grade catalysts for clean energy production. The concept of bionanomaterials for energy applications is reviewed with respect to potential fuel cell applications, bio‐catalytic upgrading of oils and manufacturing ‘drop‐in fuel’ precursors. Cheap, effective biomaterials would facilitate progress towards dual development goals of sustainable consumption and production patterns and help to ensure access to affordable, reliable, sustainable and modern energy.

Five gram negative and two gram positive bacterial strains known for their heavy metal tolerance or ability to reduce metal ions were coated with Pd(0) nanoparticles (NPs) via reduction of soluble Pd(II) ions under H2 following an initial uptake of PdCl42- without added electron donor ('biosorption'), where the gram negative strains had a ~5-fold greater capacity for Pd(II). Cupriavidis metallidurans accumulated Pd(II) exceptionally; the possibility of reduction to Pd(0) via an endogenous electron donor was not discounted. The initial rate of subsequent H2-mediated Pd(II) reduction correlated with the Pd(II) removed during biosorption (r2=0.9). TEM showed strain-specific variations of Pd-NPs. At a 1:3 loading of Pd:biomass the cell surfaces of Escherichia coli and Desulfovibrio desulfuricans showed uniform coverage with small NPs with the other strains showing larger aggregates. NPs made by the gram positive cells appeared larger than their gram negative counterparts. At a loading of 1:19 all were active catalysts in Cr(VI) reduction and in two Heck coupling reactions. BioPdE. coli and bioPdD. desulfuricans and bioPdA. oxydans were consistently the best and worst catalysts respectively. BioPdE. coli was further tested as a process catalyst according to industrial protocols in Heck and Suzuki coupling reactions. Laboratory and industrial tests (coupling of phenyl iodide and ethyl acrylate) gave 75% and 78% conversion to ethyl cinnamate, respectively. The biomaterial catalysed Heck and Suzuki reactions using bromoacetophenone and 4-bromoanisole (Heck) and 4-chloroanisole (Suzuki) but not 3-chlorotoluene. In accordance with known chemical catalysis the catalytic efficacy was related to electron-withdrawing substituents on the phenyl ring, with more than 90% conversion (Suzuki) using 4-bromobenzotrifluoride.

The Heck coupling of iodobenzene with ethyl acrylate or styrene was used to assess the catalytic properties of biogenic nanoparticles of palladium supported upon the surface of bacterial biomass (bioPd), this approach combining advantages of both homogeneous and heterogeneous catalysts. The biomaterial was comparably active or superior to colloidal Pd in the Heck reaction, giving a final conversion of 85% halide and initial rate of 0.17 mmol/min for the coupling of styrene and iodobenzene compared to a final conversion of 70% and initial rate of 0.15 mmol/min for a colloidal Pd catalyst under the same reaction conditions at 0.5 mol.% catalyst loading. It was easily separated from the products under gravity or by filtration for reuse with low loss or agglomeration. When compared to two alternative palladium catalysts, commercial 5% Pd/C and tetraalkylammonium-stabilised palladium clusters, the bioPd was successfully reused in six sequential alkylations with only slight decreases in the rate of reaction as compared to virgin catalyst (initial rate normalised for g Pd decreased by 5% by the 6th run with bioPd catalyst cf. a decrease of 95% for Pd/C). A re-usable Pd-catalyst made cheaply from bacteria left over from other processes would impact on both conservation of primary sources via reduced metal losses in industrial application and the large environmental demand of primary processing from ores.

The enzyme urease drives the hydrolysis of urea leading to the release of ammonium ions and bicar- bonate; in the presence of calcium, the rise in pH leads to increased calcium carbonate saturation and the subsequent precipitation of calcite. Although such alkalinizing ureol- ysis is widespread in nature, most studies have focussed on bacteria (i.e. indigenous communities or urease-active Sporosarcina pasteurii) for calcite precipitation technolo- gies. In this study, urease-active jack bean meal (from the legume Canavalia ensiformis) was used to drive calcite precipitation. The rates of ureolysis (kurea), determined from measured NH4 ? , enabled a direct comparison to microbial ureolysis rates reported in literature. It is also demonstrated that a simple single reaction model approach can simulate calcite precipitation very effectively (3-6 % normalised root-mean-square deviation). To investigate the reduction of permeability in porous media, jack bean meal (0.5 g L -1 ) and solutions (400 mM urea and CaCl2) were simultaneously pumped into a borosilicate bead column. One-dimensional magnetic resonance profiling techniques were used, non-invasively, for the first time to quantify the porosity changes following calcite precipitation. In addi- tion, two-dimensional slice selective magnetic resonance images (resolution of *0.5 9 1.0 mm) revealed that the exact location of calcite deposition was within the first 10 mm of the column. Column sacrifice and acid digestion also confirmed that 91.5 % of calcite was located within the first 14 mm of the column. These results have impor- tant implications for the design of future calcite precipi- tation technologies and present a possible alternative to the well known bacterial approaches.

This paper describes the preparation and morphological and fine structural characteristics of biologically derived ruthenium and bimetallic palladium/ruthenium nanoparticles. Cells of E. coli strain MC400 were used for production of bio-supported Ru and Pd/Ru bimetallic nanoparticles (bio-Ru NPs and bio-Pd/Ru NPs). High-resolution scanning transmission electron microscopy with a high-angle annular dark field detector and energy dispersive X-ray spectrometry attachment and elemental mapping was used to investigate the bio-supported synthesis of Ru and Ru/Pd NPs. Ru3+ ions were reduced by E. coli cells to the metallic state via bio-mineralisation process using hydrogen as a reducing agent. It was observed that Ru NPs were associated with the periplasmic region of E. coli, whereas Pd NPs were abundant in the periplasm and cytoplasm of the cells. Bimetallic Pd/Ru nanoparticles were observed only on the perimeter of the cells. Bio-Pd/RuE.coli preparations contain simultaneously Pd NPs, Ru NPs and Pd/Ru NPs which makes them a unique candidate for a heterogeneous catalyst. Possible configurations of the bimetallic NPs are discussed.

Microbial solar biofuels offer great promise for future sustainable food, fuels and chemicals but are limited by low productivities and a requirement for large land areas to harvest sunlight. A 71 % increase in combined photosynthetic activity was achieved by illuminating both Rhodobacter sphaeroides and Arthrospira (Spirulina) platensis from a single beam of simulated sunlight, divided using a dichroic mirror. Therefore, this technique is termed ‘dichroic beam-sharing’, in which the complementary action spectra of two different useful micro-organisms, belonging to green and purple groups, is exploited and allows a single beam of sunlight to be shared efficiently between separate photobioreactors. Because the action spectra of these two organisms are typical of large groups, this novel method could increase the productivity of photosynthetic micro-organisms in the production of diverse commodities. Electronic supplementary material The online version of this article (doi:10.1007/s10529-012-1021-5) contains supplementary material, which is available to authorized users.

BACKGROUND Desulfovibrio spp. biofabricate metallic nanoparticles (e.g. ‘Bio-Pd’) which catalyse the reduction of Cr(VI) to Cr(III) and dehalogenate polychlorinated biphenyls (PCBs). Desulfovibrio spp. are anaerobic and produce H2S, a potent catalyst poison, whereas Escherichia coli can be pre-grown aerobically to high density, has well defined molecular tools, and also makes catalytically-active ‘Bio-Pd’. The first aim was to compare ‘Bio-Pd’ catalysts made by Desulfovibrio spp. and E. coli using suspended and immobilised catalysts. The second aim was to evaluate the potential for Bio-Pd-mediated dehalogenation of PCBs in used transformer oils, which preclude recovery and re-use. RESULTS Catalysis via Bio-PdD. desulfuricans and Bio-PdE. coli was compared at a mass loading of Pd:biomass of 1:3 via reduction of Cr(VI) in aqueous solution (immobilised catalyst) and hydrogenolytic release of Cl - from PCBs and used transformer oil (catalyst suspensions). In both cases Bio-PdD. desulfuricans outperformed Bio-Pd E. coli by ~3.5-fold, attributable to a ~3.5-fold difference in their Pd-nanoparticle surface areas determined by magnetic measurements (Bio-PdD. desulfuricans) and by chemisorption analysis (Bio-PdE. coli). Small Pd particles were confirmed on D. desulfuricans and fewer, larger ones on E. coli via electron microscopy. BioPdD. desulfuricans-mediated chloride release from used transformer oil (5.6 0.8 g mL -1 ) was comparable to that observed using several PCB reference materials. CONCLUSIONS At a loading of 1:3 Pd: biomass Bio-PdD. desulfuricans is 3.5-fold more active than BioPdE. coli, attributable to the relative catalyst surface areas reflected in the smaller nanoparticle sizes of the former. This study also shows the potential of Bio-PdD. desulfuricans to remediate used transformer oil.

Aqueous wastes from nuclear fuel reprocessing present special problems of radiotoxicity of the active species. Cells of Serratia sp. were found previously to accumulate high levels of hydrogen uranyl phosphate (HUP) via the activity of a phosphatase enzyme. Uranium is of relatively low radiotoxicity whereas radionuclide fission products such as 90Sr and 137Cs are highly radiotoxic. These radionuclides can be co-crystallized, held within the bio-HUP “host” lattice on the bacterial cells and thereby removed from contaminated solution, depending on continued phosphatase activity. Radiostability tests using a commercial 60Co γ-source showed that while cell viability and activity of purified phosphatase were lost within a few hours on irradiation, whole-cell phosphatase retained 80% of the initial activity, even after loss of cell culturability, which was increased to 100% by the incorporation of mercaptoethanol as an example radioprotectant, beyond an accumulated dose of >1.3 MGy. Using this co-crystallization approach (without mercaptoethanol) 137Cs+ and 85Sr2+ were removed from a simulated waste selectively against a 33-fold excess of Na+. Biotechnol. Bioeng. 2012; 109:1937–1946. © 2012 Wiley Periodicals, Inc.

The biomanufacture of two types of platinum bionanoparticle (bioNP) using Escherichia coli MC4100(1% and 20% by mass metal loading) together with a method for both liberating the nanoparticles (NPs) from the bacterial layer and their subsequent critical cleaning is reported. The possibility of an enantiomeric excess of chiral kink sites forming on the surface of the Pt nanoparticles produced by the bacteria was investigated using the electrooxidation of D- and L-glucose as the chiral probe. Transmission electron microscopy revealed that the Pt bioNPs (after recovery and cleaning) were typically 2.3 ± 0.7 nm (1% loading) and 4.5 ± 0.7 nm (20% loading) in diameter. The D- and L-glucose electrooxidation measurements did not give rise to any chiral response using either of the Pt bioNPs types but did display differing CV profiles. This suggested that the overall surface morphology of each bioNP could be controlled by the degree of metal loading but that no enantiomeric excess of intrinsically chiral surface kink sites was present.

The selectivity towards 1,4-butynediol hydrogenation of both a standard 5 wt % Pt on graphite supported catalyst and a biogenic Pt analogue is reported. In both cases, it is determined using cyclic voltammetry that step sites afford the greatest extent of hydrogenation and that deliberate blocking of such sites gives rise to significant selectivity in favor of the 1,4-butenediol product. For the 5 wt % Pt/graphite catalyst, irreversible adsorption of bismuth was used as the step site blocking agent. In the case of the biogenic Pt nanoparticles (NPs) synthesized within the bacterium Escherichia coli, residual molecular organic fragments, left over after chemical cleaning and subsequent separation from the bacterial support, were observed to have accumulated preferentially at defect sites. This phenomenon facilitated an increase in selectivity toward alkenic products of up to 1.4 during hydrogenation of the alkyne. When biogenic NPs of platinum supported upon bacterial biomass were also investigated, they too were found to be active and selective although selectivity toward 1,4-butenediol was optimized only after the particles were chemically cleaned and separated from the biomass. Bi-poisoned 5% Pt on graphite, although highly selective, gave half the reaction rate of the biogenic counterpart (20% and 45% conversion of starting material respectively after 2 h), but the latter exhibited less selectivity for butenediol (0.7 and 0.9 respectively). It is proposed therefore that such biogenic materials may potentially act in a similar manner to Lindlar-type catalysts, used extensively in organic synthesis for selective hydrogenation of alkynes, in which an additive partially poisons metal sites but without the associated hazards of toxic heavy metals such as lead being present.

One of the most toxic byproducts of nuclear power and weapons production is the transuranics, which have a high radiotoxicity and long biological half-life due to their tendency to accumulate in the skeletal system. This accumulation is inhomogeneous and has been associated with the chemical properties and structure of the bone material rather than its location or function. This suggests a chemical driving force to incorporation and requires an atomic scale mechanistic understanding of the incorporation process. Here we propose a new incorporation mechanism for trivalent actinides and lanthanides into synthetic and biologically produced hydroxyapatite. Time-resolved laser fluorescence spectroscopy and extended X-ray absorption fine structure have been used to demonstrate that trivalent actinides and lanthanides incorporate into the amorphous grain boundaries of apatite. This incorporation site can be used to explain patterns in uptake and distribution of radionuclides in the mammalian skeletal system.

With the recent Fukushima incident, there is an urgent need to find cost effective and workable permeable reactive barrier (PRBs) for the remediation/retardation of problematic radionuclides. Catfish bones were calcined at various temperatures (400­1100°C) to remove the organic matter (87.1mg·g ¹1 ) and to change the structural properties of the hydroxyapatite (HAP). Increasing temperatures increased the HAP crystallinity as indicated by a decrease in lattice strain (0.0098 to 0.00135) and an increase in crystallite sizes (5.0 © 10 ¹8 to 7.7 © 10 ¹8 m). There was also an observed decrease in specific surface areas (98.9 to 0.99m 2 ·g ¹1 ) and increase in particle sizes (50 to 1000nm). The sorption densities of Sr 2+ decreased with increasing calcination temperatures, from 0.34 to 0.05mmol·g ¹1 . However, once normalized for surface area, the sorption densities increased from 1.8 to 5.9mmol·m¹2. Overall, this research has important implications for the design of hydroxyapatite PRBs with higher calcination temperatures producing a more reactive material with larger particle sizes for increased permeability. Lower calcination temperatures produced amorphous HAP material, which released more aqueous PO4 3¹ and resulted in the precipitation of strontium phosphates, ultimately reducing the permeability of PRBs. [doi:10.2320/matertrans.M-M2012813]

We report a novel biochemical method based on the sacrificial hydrogen strategy to synthesise bimetallic Au/Pd nanoparticles supported on bacterial cells. The synergistic effect of Au/Pd over monometallic preparations was demonstrated in the oxidation of benzyl alcohol. The bioinorganic catalysts outperformed a commercial Pd catalyst (5% Pd/C) showing no deactivation and high selectivity towards benzaldehyde.

Over the past 30 years, the literature has burgeoned with bioremediation approaches to heavy metal removal from wastes. The price of base and precious metals has also increased. With the resurgence of nuclear energy, uranium has become a strategic resource. Other noncarbon energy technologies are driven by the need to reduce CO 2 emissions. The ‘new biohydrometallurgy’ we describe unites these drivers by the concept of conversion of wastes into new materials for environmental applications. The new materials, fashioned, bottom-up, into nanomaterials under biocontrol, can be termed ‘functional bionanomaterials’. This new discipline, encompassing waste treatment along with nanocatalysis or other applications, can be summarized as ‘environmental bionanotechnology’. Several case histories illustrate the scope and potential of this concept. The research highlights biogenic nuclear waste remediation, Pd and Pt bionanocatalysts for environment and energy, Au oxidation bionanocatalysts from jewelery waste, optically active bioproducts from Se oxyanions, and nanoscale magnets biofabricated from Fe (III) wastes.

Perceived environmental problems of nuclear fuel fabrication, use and treatment limit the acceptability of nuclear power as an alternative to fossil fuels. This applies to nuclear fuel processing and reprocessing but contamination also occurs at source via run-offs from current and historic mining activities. The price of uranium (U3O8) in the1990s was US$10/lb but is currently US$58/lb, peaking in 2007 at US$135/lb. With the potential global expansion of nuclear power as an alternative to fossil fuels the market and strategic values of U will rise. A new biotechnology was demonstrated for efficient recovery of U from mine waters as pure hydrogen uranyl phosphate (HUP) but an economic assessment (discounting the value of U) showed that the limitation as a waste treatment process was the cost of the phosphate feed supplement which contained 1 mol/mol phosphate. We describe the use of phytic acid (inositol phosphate; 6 mol phosphate/mol), a ubiquitous plant waste, to support the removal of uranium as HUP by an immobilised cell reactor and shift the focus away from bioremediation to value product manufacturing from wastes, and resource efficiency.

Hydroxyapatites were analysed using electron microscopy, X-ray diffraction (XRD) and X-ray fluorescence (XRF) analysis. Examination of a bacterially produced hydroxyapatite (Bio-HA) by scanning electron microscopy showed agglomerated nano-sized particles; XRD analysis confirmed that the Bio-HA was hydroxyapatite, with an organic matter content of 7.6%; XRF analysis gave a Ca/P ratio of 1.55, also indicative of HA. The size of the Bio-HA crystals was calculated as ~25 nm from XRD data using the Scherrer equation, whereas Comm-HA powder size was measured as ≤ 50 μm. The nano-crystalline Bio-HA was ~7 times more efficient in removing Sr(2+) from synthetic groundwater than Comm-HA. Dissolution of HA as indicated by the release of phosphate into the solution phase was higher in the Comm-HA than the Bio-HA, indicating a more stable biomaterial which has a potential for the remediation of contaminated sites.

Escherichia coli produces at least three [NiFe] hydrogenases (Hyd-1, Hyd-2 and Hyd-3). Hyd-1 and Hyd-2 are membrane-bound respiratory isoenzymes with their catalytic subunits exposed to the periplasmic side of the membrane. Hyd-3 is part of the cytoplasmically oriented formate hydrogenlyase complex. In this work the involvement of each of these hydrogenases in Pd(II) reduction under acidic (pH 2.4) conditions was studied. While all three hydrogenases could contribute to Pd(II) reduction, the presence of either periplasmic hydrogenase (Hyd-1 or Hyd-2) was required to observe Pd(II) reduction rates comparable to the parent strain. An E. coli mutant strain genetically deprived of all hydrogenase activity showed negligible Pd(II) reduction. Electron microscopy suggested that the location of the resulting Pd(0) deposits was as expected from the subcellular localization of the particular hydrogenase involved in the reduction process. Membrane separation experiments established that Pd(II) reductase activity is membrane-bound and that hydrogenases are required to initiate Pd(II) reduction. The catalytic activity of the resulting Pd(0) nanoparticles in the reduction of Cr(VI) to Cr(III) varied according to the E. coli mutant strain used for the initial bioreduction of Pd(II). Optimum Cr(VI) reduction, comparable to that observed with a commercial Pd catalyst, was observed when the bio-Pd(0) catalytic particles were prepared from a strain containing an active Hyd-1. The results are discussed in the context of economic production of novel nanometallic catalysts.

Metal phosphate deposited enzymatically on Serratia sp. has been used successfully for the removal of radionuclides from aqueous flows. Previous studies using biogenic hydrogen uranyl phosphate (HUP) on Serratia sp. biofilm showed removal of 100% of (90)Sr, (137)Cs, and (60)Co via their intercalation into biogenic HUP crystals. Zirconium phosphates (ZrP) offer a potential non-toxic and non-radioactive alternative to HUP for water decontamination. A method was developed for biomanufacturing ZrP. Biogenic ZrP removed ca. 100% of Sr(2+) and Co(2+) (0.5 mM) from solutions to a molar ratio at saturation of ca. 1:0.6 for both Zr:Sr and Zr:Co. The potential for drinking water decontamination via bio-ZrP is discussed with respect to bio-HUP and also other commercially available materials.

Palladium catalyst samples were prepared upon bacterial biomass supports (Gram-positive A. oxidans and Gram-negative R. capsulatus) and tested in the partial hydrogenation of 2-butyne-1,4-diol to 2-butene-1,4-diol. The objectives of the study were to assess the effects of operating conditions in the stirred autoclave upon the reaction conversion and selectivity and to compare the biologically supported palladium (BioPd) catalyst performance with that of a conventionally supported catalyst. Variables investigated included solvent, stirring speed, and catalyst metal loading. A maximum selectivity toward 2-butene-1,4-diol of 0.98 was observed in a solvent composed of 5% isopropyl alcohol (2-propanol) in water at a conversion of 75% 2-butyne-1,4-diol for the Pd/A. oxidans catalyst. The Pd/R.capsulatas catalyst showed a maximum selectivity of 1.0 at a conversion of 62.6%. Concentration profiles of the different hydrogenation products were fitted using a Langmuir−Hinshelwood expression, which showed a higher fi...

The versatility and reaction specificity of a novel bioinorganic catalyst is demonstrated in various reactions. Palladized cells (bioPd) of the sulphate-reducing bacterium Desulfovibrio desulfuricans showed an increased product selectivity and a catalytic activity comparable to a commercial Pd catalyst in several industrially relevant hydrogenations and hydrogenolyses (reductive dehalogenations). The ability of palladized cells to promote the reductive debromination of a polybrominated diphenyl ether (PBDE #47) is demonstrated, although chemically reduced Pd(II) and commercial Pd(0) were more effective debromination agents. Polybrominated diphenyl ethers are being supplanted as flame retardants by other compounds, e.g. tris(chloroisopropyl)phosphate (TCPP), the concentration of which was seen to increase approximately 10-fold in groundwater samples between 2000 and 2004. BioPd dechlorinated TCPP in groundwater samples with90% recovery of free chloride ion, and was five times more effective than using commercial Pd(0) catalyst. Examination of the spent groundwater using 31P NMR showed a phosphorus species novel to the bioPd-treated solution, which was not evident in a commercial reference sample of TCPP.

This study was aimed at the development of a new heterogeneous Pd catalyst based on biologically mineralised palladium (Bio-Pd). Desulfovibrio desulfuricans was used to reduce Pd(II) to nanocrystalline Pd embedded in the bacterial surface. In this way the biomass provides support and prevents coalescence of the palladium nanoparticles. Palladised biomass exhibits catalytic activity, which was demonstrated in a range of applications including reduction, oxidation and hydrogenation reactions. Preparation of Bio-Pd under various conditions leads to the formation of a supported palladium catalyst with potentially different catalytic properties according to the preparation method.

Perceived environmental problems of nuclear fuel fabrication, use and treatment limit the acceptability of nuclear power as an alternative to fossil fuels. This applies to nuclear fuel processing and reprocessing but contamination also occurs at source via run-offs from current and historic mining activities. The price of uranium (U3O8) in the1990s was US$10/lb but is currently US$ 58/lb, peaking in 2007 at US$135/lb. With the potential global expansion of nuclear power as an alternative to fossil fuels the market and strategic values of U will rise. A new biotechnology was demonstrated for efficient recovery of U from minewaters as pure hydrogen uranyl phosphate (HUP) but an economic assessment (discounting the value of U) showed that the limitation as a waste treatment process was the cost of the phosphate feed supplement which contained 1 mol/mol phosphate. We describe the use of phytic acid (inositol phosphate; 6 mol phosphate/mol), a ubiquitous plant waste, to support the removal of uranium as HUP by an immobilised cell reactor and shift the focus from away bioremediation to value product manufacturing from wastes, and resource efficiency.

Nanoparticles of palladium were obtained with the help of hydrogen-oxidising, metal- reducing bacteria and used for the production of electricity in a proton exchange membrane (PEM) fuel cell. Earlier works have shown that palladised cells of Escherichia coli and Desulfovibrio desulfuricans (Bio-PdE.coli and Bio-PdD.desulfuricans, respectively) appeared similar by electron microscopy and were comparably active in a chemical test reaction. When tested in a PEM fuel cell they produced 0.018 and 0.108 W, respectively. Electron paramagnetic resonance analysis of Bio-PdE.coli mixed with activated carbon showed paramagnetic activity. However, Bio-PdD.desulfuricans under the same conditions quenched the intrinsic EPR signal. This quenching is indicative of the magnetic properties of the particles. The magnetic behaviour of Pd nanoparticles was theoretically predicted for particles between 10 and 20 nm in diameter and can be experimentally confirmed by EPR measurements.

This study describes biofilm formation as a non line-of-sight coating method on support materials such as polyurethane foam, porous glass, polypropylene (PP) and titanium alloy, using a Serratia sp., which can manufacture extracellular nanoscale scaffolded hydroxyapatite (HA) crystals via enzymatic cleavage of glycerol 2-phosphate (G2P) in the presence of CaCl2. Various microscopies and non-invasive magnetic resonance imaging were used to visualize the biofilm coating on the support surface. A novel micromanipulation technique was used to estimate the adhesive strength of native and HA-mineralized biofilms. The biofilm with HA was up to forty times stronger than that without HA. A coating of nano-HA (> 80 m) onto a biofilm-Ti disc was achieved.

Bio-manufacturing of nano-scale palladium was achieved using bacterial cells. Highly active Pd-catalyst (Bio-Pd) produced by an E. coli mutant gave power output in a fuel cell. Up to ~115% of the maximum power generation was achieved by electrodes of Bio-Pd catalysts from Escherichia coli, compared to that from a commercial-Pd electrode (~0.099 W). A bio-precious-metals (Bio-PM) catalyst made directly from an industrial reprocessing solution by the E. coli was also made into fuel cell electrodes and ~0.06W of maximum power generation was observed.

Biological methods of hydrogen production are preferable to chemical methods because of the possibility to use sunlight, CO2 and organic wastes as substrates for environmentally benign conversions, under moderate conditions. By combining different microorganisms with different capabilities, the individual strengths of each may be exploited and their weaknesses overcome. Mechanisms of bio-hydrogen production are described and strategies for their integration are discussed. Dual systems can be divided broadly into wholly light-driven systems (with microalgae/cyanobacteria as the 1st stage) and partially light-driven systems (with a dark, fermentative initial reaction). Review and evaluation of published data suggests that the latter type of system holds greater promise for industrial application. This is because the calculated land area required for a wholly light-driven dual system would be too large for either centralised (macro-) or decentralised (micro-) energy generation. The potential contribution to the hydrogen economy of partially light-driven dual systems is overviewed alongside that of other bio-fuels such as bio-methane and bio-ethanol.