6 research outputs found
Enhanced hydrogenation catalyst synthesized by Desulfovibrio desulfuricans exposed to a radio frequency magnetic field
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(University of Cardiff, UK) to show their unpublished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/1UK Research & Innovation (UKRI)
Biotechnology and Biological Sciences Research Council (BBSRC) BB/C516128/1UK Research & Innovation (UKRI)Natural Environment Research Council (NERC) NE/L014076/1Royal Society of London
European CommissionSpanish Government Sistema Nacional de Garantia Juvenil grant PEJ-2014-P-0039
Biosynthesis of zinc sulfide quantum dots using waste off-gas from a metal bioremediation process
Waste H2S biogas from a mine-water remediation bioprocess is used to make zinc sulfide quantum dots which are identical to ZnS QDs made by chemical methods.</p
The Bioreduction of Selenite under Anaerobic and Alkaline Conditions Analogous to Those Expected for a Deep Geological Repository System
The environmental conditions for the planned geological disposal of radioactive waste
—including hyper-alkaline pH, radiation or anoxia—are expected to be extremely harsh for microbial
activity. However, it is thought that microbial communities will develop in these repositories, and this
would have implications for geodisposal integrity and the control of radionuclide migration through
the surrounding environment. Nuclear waste contains radioactive isotopes of selenium (Se) such
as 79Se, which has been identified as one of the main radionuclides in a geodisposal system. Here,
we use the bacterial species Stenotrophomonas bentonitica, isolated from bentonites serving as an
artificial barrier reference material in repositories, to study the reduction of selenite (SeIV) under
simulated geodisposal conditions. This bacterium is able to reduce toxic SeIV anaerobically from a
neutral to alkaline initial pH (up to pH 10), thereby producing elemental selenium (Se0) nanospheres
and nanowires. A transformation process from amorphous Se (a-Se) nanospheres to trigonal Se
(t-Se) nanowires, through the formation of monoclinic Se (m-Se) aggregates as an intermediate step,
is proposed. The lesser solubility of Se0 and t-Se makes S. bentonitica a potential candidate to positively
influence the security of a geodisposal system, most probably with lower efficiency rates than those
obtained aerobically.This work was supported by the Euratom research and training programme 2014–2018 under grant
agreement no. 66188
Upconversion of Cellulosic Waste Into a Potential “Drop in Fuel” via Novel Catalyst Generated Using Desulfovibrio desulfuricans and a Consortium of Acidophilic Sulfidogens
The authors acknowledge with thanks, use of GC-FID/GC-MS supplied by Dr. Daniel Lester within the Polymer Characterization Research Technology Platform, University of Warwick and the help of Drs. B. Kaulich, T. Araki,and M. Kazemian at beamline IO8, Diamond Light Source, United Kingdom, who funded the synchrotron study (Award No. SP16407: Scanning X-ray Microscopy Study of Biogenic Nanoparticles; Improved Bionanocatalysts by Design) on I08 Scanning X-ray Microscopy beamline (SXM).The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fmicb.2019.00970/full#supplementary-materialBiogas-energy is marginally profitable against the “parasitic” energy demands of processing biomass. Biogas involves microbial fermentation of feedstock hydrolyzate generated enzymatically or thermochemically. The latter also produces 5-hydroxymethyl furfural (5-HMF) which can be catalytically upgraded to 2, 5-dimethyl furan (DMF), a “drop in fuel.” An integrated process is proposed with side-stream upgrading into DMF to mitigate the “parasitic” energy demand. 5-HMF was upgraded using bacterially-supported Pd/Ru catalysts. Purpose-growth of bacteria adds additional process costs; Pd/Ru catalysts biofabricated using the sulfate-reducing bacterium (SRB) Desulfovibrio desulfuricans were compared to those generated from a waste consortium of acidophilic sulfidogens (CAS). Methyl tetrahydrofuran (MTHF) was used as the extraction-reaction solvent to compare the use of bio-metallic Pd/Ru catalysts to upgrade 5-HMF to DMF from starch and cellulose hydrolyzates. MTHF extracted up to 65% of the 5-HMF, delivering solutions, respectively, containing 8.8 and 2.2 g 5-HMF/L MTHF. Commercial 5% (wt/wt) Ru-carbon catalyst upgraded 5-HMF from pure solution but it was ineffective against the hydrolyzates. Both types of bacterial catalyst (5wt%Pd/3-5wt% Ru) achieved this, bio-Pd/Ru on the CAS delivering the highest conversion yields. The yield of 5-HMF from starch-cellulose thermal treatment to 2,5 DMF was 224 and 127 g DMF/kg extracted 5-HMF, respectively, for CAS and D. desulfuricans catalysts, which would provide additional energy of 2.1 and 1.2 kWh/kg extracted 5-HMF. The CAS comprised a mixed population with three patterns of metallic nanoparticle (NP) deposition. Types I and II showed cell surface-localization of the Pd/Ru while type III localized NPs throughout the cell surface and cytoplasm. No metallic patterning in the NPs was shown via elemental mapping using energy dispersive X-ray microanalysis but co-localization with sulfur was observed. Analysis of the cell surfaces of the bulk populations by X-ray photoelectron spectroscopy confirmed the higher S content of the CAS bacteria as compared to D. desulfuricans and also the presence of Pd-S as well as Ru-S compounds and hence a mixed deposit of PdS, Pd(0), and Ru in the form of various +3, +4, and +6 oxidation states. The results are discussed in the context of recently-reported controlled palladium sulfide ensembles for an improved hydrogenation catalyst.This project was funded by NERC grant NE/L014076/1 to LM (Program: “Resource Recovery from Wastes”). The Science City Photoemission Facility used in this research was funded through the Science Cities Advanced Materials Project 1: “Creating and Characterizing Next Generation of Advanced Materials” with support from AWM and ERDF funds. The microscopy work was conducted at “Centro de Instrumentación Cientifica” at the University of Granada, Spain. This work was partially supported by the Spanish Government Sistema Nacional de Grantia Juvenil grant PEJ-2014-P-00391 (Promocion de Empleo Joven e Implantacion de la Garantia Juvenil 2014, MINECO) with a scholarship to JGB
Coupled Biohydrogen Production and Bio-Nanocatalysis for Dual Energy from Cellulose: Towards Cellulosic Waste Up-Conversion into Biofuels
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