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Thomas J. Aspray
School of Energy, Geoscience, Infrastructure and Society, Heriot-Watt University, Edinburgh EH14 4AS, Scotland, UK

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Short communication
Published: 09 March 2021 in Waste Management
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Biological tests are widely used to assess composting process status and finished material stability. Although compost stability is known to be influenced by moisture content (MC) and storage duration, there is a lack of data supporting boundary limits for standardised testing. Using the ORG0020 dynamic respiration test we assessed the stability of materials from different commercial composting sites processing only green waste or mixed green and food waste. Samples were tested at three different MC following adjustment with the ‘fist’ test within the range 40–60%. The results showed manipulation of MC within this range could have significant impact on measured stability for some but not all samples. Two samples reported significantly higher activity when MC was manipulated from ~50% to ~60%. For storage duration, samples showed significant decrease in measured activity over several weeks of cold storage. However, there was no significant difference in stability for samples tested up to nine days from receipt. The results of this research will support decisions relating to the boundary limits for moisture content and storage time for the ORG0020 test. The results will also provide insight to the wider range of biological tests used to assess compost stability.

ACS Style

Nisha N. Gurusamy; Natalie Puffer; Coen de Jongh; Cristina Rodriguez Gil; Thomas J. Aspray. Effect of initial moisture content and sample storage duration on compost stability using the ORG0020 dynamic respiration test. Waste Management 2021, 125, 215 -219.

AMA Style

Nisha N. Gurusamy, Natalie Puffer, Coen de Jongh, Cristina Rodriguez Gil, Thomas J. Aspray. Effect of initial moisture content and sample storage duration on compost stability using the ORG0020 dynamic respiration test. Waste Management. 2021; 125 ():215-219.

Chicago/Turabian Style

Nisha N. Gurusamy; Natalie Puffer; Coen de Jongh; Cristina Rodriguez Gil; Thomas J. Aspray. 2021. "Effect of initial moisture content and sample storage duration on compost stability using the ORG0020 dynamic respiration test." Waste Management 125, no. : 215-219.

Original article
Published: 10 February 2021 in Indoor Air
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Aerosols are readily transported on airstreams through building sanitary plumbing and sewer systems, and those containing microbial pathogens (known as bioaerosols) are recognized as contributors to infection spread within buildings. When a defect occurs in the sanitary plumbing system that affects the system integrity, a cross‐transmission route is created that can enable the emission of bioaerosols from the system into the building. These emission occurrences are characterized as short‐burst events (typically 99.5%) were 11 μm anywhere in the system. Particle count was influenced by toilet flush volume, but it was not possible to determine if there was any direct influence from airflow rate since both particle and biological data showed no correlation with upward airflow rates and velocities. Typical emissions resulting from a 6 L toilet flush were in the range of 280–400 particles per second at a concentration of typically 9–12 number per cm3 and a total particle count in the region of 3000 to 4000 particles, whereas the peak emissions from a 1.2 L toilet flush were 60–80 particles per second at a concentration of 2.4–3 number per cm3 and a total particle count in the region of 886 to 1045 particles. The reduction in particles is in direct proportion to the reduction in toilet flush volume. The slit‐to‐agar sampler was able to provide viable time course CFU data and confirmed the origin of the particles to be the tracer microorganism flushed into the system. The time course data also have characteristics consistent with the unsteady nature of a toilet flush.

ACS Style

Michael Gormley; Thomas J. Aspray; David A. Kelly. Aerosol and bioaerosol particle size and dynamics from defective sanitary plumbing systems. Indoor Air 2021, 31, 1427 -1440.

AMA Style

Michael Gormley, Thomas J. Aspray, David A. Kelly. Aerosol and bioaerosol particle size and dynamics from defective sanitary plumbing systems. Indoor Air. 2021; 31 (5):1427-1440.

Chicago/Turabian Style

Michael Gormley; Thomas J. Aspray; David A. Kelly. 2021. "Aerosol and bioaerosol particle size and dynamics from defective sanitary plumbing systems." Indoor Air 31, no. 5: 1427-1440.

Preprint content
Published: 15 February 2020
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The balance of nutrients in soil is critical for microbial growth and function, and stoichiometric values below the Redfield ratio for C:N:P can negatively affect microbial ecosystem services. However, few studies have assessed the relationships between nutrient balance and biological productivity in extremely nutrient-poor habitats. The Mackay Glacier region of Eastern Antarctica is a hyper-oligotrophic ice-free desert and is an appropriate landscape to evaluate the effects of nutrient deficiency and imbalance on microbial community ecology. In a survey of multiple, widely dispersed soil samples from this region, we detected only low rates of microbial respiration, and observed that C:N:P ratios were well below those required for optimal activity. In silico metagenomic and soil isotopic ratio (δ15N) analyses indicated that the capacity for nitrogen fixation was low, but that soil microbial communities were enriched for soil nitrate assimilation processes, mostly associated with heterotrophic taxa. δ13C isotope ratio data suggested that carbon dioxide was fixed principally via the Calvin cycle. Genes involved in this pathway were common to all metagenomes and were primarily attributed to members of the dominant soil bacterial phyla: Bacteroidetes and Acidobacteria. The identification of multiple genes encoding non-photoautotrophic RUBISCO and carbon dioxide dehydrogenase enzymes in both the metagenomic sequences and assembled MAGs is suggestive of a trace-gas scavenging physiology in members of these soil communities.

ACS Style

Marc W. Van Goethem; Surendra Vikram; David W. Hopkins; Grant Hall; Stephan Woodborne; Thomas J. Aspray; Ian D. Hogg; Don A. Cowan; Thulani P. Makhalanyane. Nutrient parsimony shapes diversity and functionality in hyper-oligotrophic Antarctic soils. 2020, 1 .

AMA Style

Marc W. Van Goethem, Surendra Vikram, David W. Hopkins, Grant Hall, Stephan Woodborne, Thomas J. Aspray, Ian D. Hogg, Don A. Cowan, Thulani P. Makhalanyane. Nutrient parsimony shapes diversity and functionality in hyper-oligotrophic Antarctic soils. . 2020; ():1.

Chicago/Turabian Style

Marc W. Van Goethem; Surendra Vikram; David W. Hopkins; Grant Hall; Stephan Woodborne; Thomas J. Aspray; Ian D. Hogg; Don A. Cowan; Thulani P. Makhalanyane. 2020. "Nutrient parsimony shapes diversity and functionality in hyper-oligotrophic Antarctic soils." , no. : 1.

Short communication
Published: 24 June 2019 in Waste Management
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Green waste composting materials and finished composts were collected from different commercial ex situ composting sites all treating source segregated green waste feedstocks. Stability of each material was determined using the standard ORG0020 dynamic respiration test. To assess whether stability could be used as an indicator for the potential suitability of green waste composting materials and finished composts as amendments for soil bioremediation, comparison was made with alkane and aromatic hydrocarbon degrader abundance determined using a quantitative PCR (qPCR) approach. Specifically, primers targeting alkB and, polyaromatic hydrocarbon ring-hydroxylating dioxygenases genes (PAH-RHD) of Gram positive (GP) and Gram negative (GN) populations were used for qPCR analysis. The results showed no direct correction between compost stability and gene abundance. Further, increase in alkB gene abundance was not linked to PAH-RHD gene abundance. The results support the use of qPCR as a tool for screening organic amendments on a site by site basis for soil bioremediation treatment.

ACS Style

Diana Guillen Ferrari; Jennifer Pratscher; Thomas J. Aspray. Assessment of the use of compost stability as an indicator of alkane and aromatic hydrocarbon degrader abundance in green waste composting materials and finished composts for soil bioremediation application. Waste Management 2019, 95, 365 -369.

AMA Style

Diana Guillen Ferrari, Jennifer Pratscher, Thomas J. Aspray. Assessment of the use of compost stability as an indicator of alkane and aromatic hydrocarbon degrader abundance in green waste composting materials and finished composts for soil bioremediation application. Waste Management. 2019; 95 ():365-369.

Chicago/Turabian Style

Diana Guillen Ferrari; Jennifer Pratscher; Thomas J. Aspray. 2019. "Assessment of the use of compost stability as an indicator of alkane and aromatic hydrocarbon degrader abundance in green waste composting materials and finished composts for soil bioremediation application." Waste Management 95, no. : 365-369.

Journal article
Published: 01 January 2018 in Waste Management
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A novel process has been developed for the selective removal of protein from pot ale with recovered protein holding potential as a value-added by-product for the whisky industry. The purpose of this work was to assess the effect of deproteination on pot ale physicochemical characterisation and anaerobic digestion (AD) treatment. Pot ales were taken from five malt whisky distilleries and tested untreated, after centrifugation/filtration and after deproteination at laboratory or pilot scale. At laboratory scale, the deproteination process removed around 20% of total chemical oxygen demand (tCOD) from untreated pot ale and at least 30% dissolved copper from centrifuged pot ale. Biochemical methane potential of untreated, filtered and deproteinated pot ale obtained at pilot scale has been determined using two types of inocula from different source. Average methane yield values of 554±67, 586±24 and 501±23 Nl CH4 kg(-1) VS were obtained for untreated, filtered and deproteinated pot ale respectively. A significant difference in methane yield was only observed for untreated pot ale using the two types of inocula. Specifically, when using a non-adapted inoculum untreated pot ale biogas yield was significant lower suggesting inhibition of the AD process. As no significant differences were found for treated pot ale (filtered and deproteinated) with the two inocula it suggests, deproteination may have a positive effect on AD start-up. The results present a clear case for continuation of this work and evaluating the effect on continuous AD.

ACS Style

Raquel Barrena; Julio E. Traub; Cristina Rodriguez Gil; Julian A.S. Goodwin; Alan J. Harper; Nik Willoughby; Antoni Sánchez; Thomas J. Aspray. Batch anaerobic digestion of deproteinated malt whisky pot ale using different source inocula. Waste Management 2018, 71, 675 -682.

AMA Style

Raquel Barrena, Julio E. Traub, Cristina Rodriguez Gil, Julian A.S. Goodwin, Alan J. Harper, Nik Willoughby, Antoni Sánchez, Thomas J. Aspray. Batch anaerobic digestion of deproteinated malt whisky pot ale using different source inocula. Waste Management. 2018; 71 ():675-682.

Chicago/Turabian Style

Raquel Barrena; Julio E. Traub; Cristina Rodriguez Gil; Julian A.S. Goodwin; Alan J. Harper; Nik Willoughby; Antoni Sánchez; Thomas J. Aspray. 2018. "Batch anaerobic digestion of deproteinated malt whisky pot ale using different source inocula." Waste Management 71, no. : 675-682.

Journal article
Published: 18 December 2017 in Sustainability
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The ORG0020 dynamic respiration test is effective at distinguishing source segregated organic waste derived composts across a wide range of stabilities when compared to other standard tests; however, using the original diaphragm pump and manifold setup, the test is affected by variability in flow rate with time and across sample replicate vessels. Here, we demonstrate the use of a multichannel peristaltic pump to deliver a more consistent air flow to individual vessels. Using finished and unfinished industry compost samples from different sites with varying stabilities, we provide evidence of greater precision of the modified setup compared to the original. Furthermore, the reduced need for air flow adjustment resulted in improved running cost efficiency with less labour demand. Analysis of compost sample oxygen demand supports the current test air flow rate of 25–75 mL min−1, although the improved air flow control will enable future narrowing of the acceptable range for better inter-laboratory performance.

ACS Style

Diana Guillen Ferrari; Graham Howell; Thomas J. Aspray. Improved Precision and Efficiency of a Modified ORG0020 Dynamic Respiration Test Setup for Compost Stability Assessment. Sustainability 2017, 9, 2358 .

AMA Style

Diana Guillen Ferrari, Graham Howell, Thomas J. Aspray. Improved Precision and Efficiency of a Modified ORG0020 Dynamic Respiration Test Setup for Compost Stability Assessment. Sustainability. 2017; 9 (12):2358.

Chicago/Turabian Style

Diana Guillen Ferrari; Graham Howell; Thomas J. Aspray. 2017. "Improved Precision and Efficiency of a Modified ORG0020 Dynamic Respiration Test Setup for Compost Stability Assessment." Sustainability 9, no. 12: 2358.

Journal article
Published: 01 January 2017 in Waste Management
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Physical contaminants (glass, metal, plastic and 'other') and stones were isolated and categorised from three finished commercial composts derived from source segregated biodegradable municipal waste (BMW). A subset of the identified physical contaminant fragments were subsequently reintroduced into the cleaned compost samples and sent to three commercial laboratories for testing in an inter-laboratory trial using the current PAS100:2011 method (AfOR MT PC&S). The trial showed that the 'other' category caused difficulty for all three laboratories with under reporting, particularly of the most common 'other' contaminants (paper and cardboard) and, over-reporting of non-man-made fragments. One laboratory underreported metal contaminant fragments (spiked as silver foil) in three samples. Glass, plastic and stones were variably underreported due to miss-classification or over reported due to contamination with compost (organic) fragments. The results are discussed in the context of global physical contaminant test methods and compost quality assurance schemes.

ACS Style

Virginia Echavarri-Bravo; Helene H. Thygesen; Thomas J. Aspray. Variability in physical contamination assessment of source segregated biodegradable municipal waste derived composts. Waste Management 2017, 59, 30 -36.

AMA Style

Virginia Echavarri-Bravo, Helene H. Thygesen, Thomas J. Aspray. Variability in physical contamination assessment of source segregated biodegradable municipal waste derived composts. Waste Management. 2017; 59 ():30-36.

Chicago/Turabian Style

Virginia Echavarri-Bravo; Helene H. Thygesen; Thomas J. Aspray. 2017. "Variability in physical contamination assessment of source segregated biodegradable municipal waste derived composts." Waste Management 59, no. : 30-36.

Journal article
Published: 01 June 2016 in Chemosphere
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Pseudomonas putida mono-species biofilms were exposed to silver nanoparticles (Ag NPs) in artificial wastewater (AW) under hydrodynamic conditions. Specifically, 48 h old biofilms received a single pulse of Ag NPs at 0, 0.01, 0.1, 1, 10 and 100 mg L−1 for 24 h in confocal laser scanning microscopy (CLSM) compatible flow-cells. The biofilm dynamics (in terms of morphology, viability and activity) were characterised at 48, 72 and 96 h. Consistent patterns were found across flow-cells and experiments at 48 h. Dose dependent impacts of NPs were then shown at 72 h on biofilm morphology (e.g. biomass, surface area and roughness) from 0.01 mg L−1. The microbial viability was not altered below 10 mg L−1 Ag NPs. The activity (based on the d-glucose utilisation) was impacted by concentrations of Ag NPs equal and superior to 10 mg L−1. Partial recovery of morphology, viability and activity were finally observed at 96 h. Comparatively, exposure to Ag salt resulted in ca. one order of magnitude higher toxicity when compared to Ag NPs. Consequently, the use of a continuous culture system and incorporation of a recovery stage extends the value of biofilm assays beyond the standard acute toxicity assessment.

ACS Style

Florian Mallevre; Teresa F. Fernandes; Thomas J. Aspray. Pseudomonas putida biofilm dynamics following a single pulse of silver nanoparticles. Chemosphere 2016, 153, 356 -364.

AMA Style

Florian Mallevre, Teresa F. Fernandes, Thomas J. Aspray. Pseudomonas putida biofilm dynamics following a single pulse of silver nanoparticles. Chemosphere. 2016; 153 ():356-364.

Chicago/Turabian Style

Florian Mallevre; Teresa F. Fernandes; Thomas J. Aspray. 2016. "Pseudomonas putida biofilm dynamics following a single pulse of silver nanoparticles." Chemosphere 153, no. : 356-364.

Journal article
Published: 11 March 2016 in Nanomaterials
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Impact of aging on nanoparticle toxicity in real matrices is scarcely investigated due to a lack of suitable methodologies. Herein, the toxicity of pristine and aged silver nanoparticles (Ag NPs) to a bioluminescent Pseudomonas putida bioreporter was measured in spiked crude and final wastewater samples (CWs and FWs, respectively) collected from four wastewater treatment plants (WWTPs). Results showed lower toxicity of pristine Ag NPs in CWs than in FWs. The effect of the matrix on the eventual Ag NP toxicity was related to multiple physico-chemical parameters (biological oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS) pH, ammonia, sulfide and chloride) based on a multivariate analysis. However, no collection site effect was concluded. Aged Ag NPs (up to eight weeks) were found less toxic than pristine Ag NPs in CWs; evident increased aggregation and decreased dissolution were associated with aging. However, Ag NPs exhibited consistent toxicity in FWs despite aging; comparable results were obtained in artificial wastewater (AW) simulating effluent. The study demonstrates the potency of performing nanoparticle acute toxicity testing in real and complex matrices such as wastewaters using relevant bacterial bioreporters.

ACS Style

Florian Mallevre; Camille Alba; Craig Milne; Simon Gillespie; Teresa F. Fernandes; Thomas J. Aspray. Toxicity Testing of Pristine and Aged Silver Nanoparticles in Real Wastewaters Using Bioluminescent Pseudomonas putida. Nanomaterials 2016, 6, 49 .

AMA Style

Florian Mallevre, Camille Alba, Craig Milne, Simon Gillespie, Teresa F. Fernandes, Thomas J. Aspray. Toxicity Testing of Pristine and Aged Silver Nanoparticles in Real Wastewaters Using Bioluminescent Pseudomonas putida. Nanomaterials. 2016; 6 (3):49.

Chicago/Turabian Style

Florian Mallevre; Camille Alba; Craig Milne; Simon Gillespie; Teresa F. Fernandes; Thomas J. Aspray. 2016. "Toxicity Testing of Pristine and Aged Silver Nanoparticles in Real Wastewaters Using Bioluminescent Pseudomonas putida." Nanomaterials 6, no. 3: 49.

Journal article
Published: 01 January 2016 in NanoImpact
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In this paper we report for the first time on the suitability of surface plasmon resonance imaging (SPRi) for performing ecotoxicity testing of nanoparticles (NPs). Specifically, the impact of silver NPs (using Ag NM-300K) and ions (using AgNO3 salt) on Salmonella Enteritidis growth was assessed in Luria Bertani medium using the culture-capture-measure (CCM) based SPRi method. Clear effects were observed at 10 mg L− 1 Ag NPs characterised by shifted SPRi detection times (TD) by ca. 2.6 h compared to the control. Comparable results were obtained using 1 mg L− 1 Ag ions. No clear effects were observed at 1 mg L− 1 Ag NPs and 0.1 mg L− 1 Ag ions. Overall results match the current trend in nanoecotoxicology using bacteria (e.g. impact of Ag NPs between 1 and 10 mg L− 1 and higher toxicity of Ag ions compared to Ag NPs). The dose dependent patterns of toxicity were coherent with those obtained using a standard plating method; however, the SPRi approach was faster (i.e. results within a few hours) and generated kinetic data (i.e. real-time monitoring). In addition, SPRi presents many valuable intrinsic advantages (e.g. label-free, multiplex, bespoke and robust) over current approaches. Consequently, a plethora of opportunities for future developments and applications of SPRi in NP testing is associated with the proof of concept reported herein.

ACS Style

Florian Mallevre; Vincent Templier; Raphael Mathey; Loic Leroy; Yoann Roupioz; Teresa Fernandes; Thomas J. Aspray; Thierry Livache. Real-time toxicity testing of silver nanoparticles to Salmonella Enteritidis using surface plasmon resonance imaging: A proof of concept. NanoImpact 2016, 1, 55 -59.

AMA Style

Florian Mallevre, Vincent Templier, Raphael Mathey, Loic Leroy, Yoann Roupioz, Teresa Fernandes, Thomas J. Aspray, Thierry Livache. Real-time toxicity testing of silver nanoparticles to Salmonella Enteritidis using surface plasmon resonance imaging: A proof of concept. NanoImpact. 2016; 1 ():55-59.

Chicago/Turabian Style

Florian Mallevre; Vincent Templier; Raphael Mathey; Loic Leroy; Yoann Roupioz; Teresa Fernandes; Thomas J. Aspray; Thierry Livache. 2016. "Real-time toxicity testing of silver nanoparticles to Salmonella Enteritidis using surface plasmon resonance imaging: A proof of concept." NanoImpact 1, no. : 55-59.

Comparative study
Published: 01 August 2015 in Waste Management
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The purpose of this work was to evaluate compost (and related industry) stability tests given recent large-scale changes to feedstock, processing techniques and compost market requirements. Five stability tests (ORG0020, DR4, Dewar self-heating, oxygen update rate (OUR) and static respiration) were evaluated on composts from ten in-vessel composting sites. Spearman rank correlation coefficients were strong for the ORG0020, OUR and DR4 (both CO2 and O2 measurement), however, OUR results required data extrapolation for highly active compost samples. By comparison the Dewar self-heating and static respiration tests had weaker correlations, in part the result of under reporting highly active, low pH samples. The findings suggest that despite differences in pre-incubation period both dynamic respiration tests (ORG0020 and DR4) are best suited to deal with the wide range of compost stabilities found.

ACS Style

Thomas J. Aspray; Mary E. Dimambro; Phil Wallace; Graham Howell; James Frederickson. Static, dynamic and inoculum augmented respiration based test assessment for determining in-vessel compost stability. Waste Management 2015, 42, 3 -9.

AMA Style

Thomas J. Aspray, Mary E. Dimambro, Phil Wallace, Graham Howell, James Frederickson. Static, dynamic and inoculum augmented respiration based test assessment for determining in-vessel compost stability. Waste Management. 2015; 42 ():3-9.

Chicago/Turabian Style

Thomas J. Aspray; Mary E. Dimambro; Phil Wallace; Graham Howell; James Frederickson. 2015. "Static, dynamic and inoculum augmented respiration based test assessment for determining in-vessel compost stability." Waste Management 42, no. : 3-9.

Journal article
Published: 01 June 2015 in Environmental Pollution
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The increasing use of silver nanoparticles (AgNPs) as a biocidal agent and their potential accumulation in sediments may threaten non-target natural environmental bacterial communities. In this study a microcosm approach was established to investigate the effects of well characterized OECD AgNPs (NM-300) on the function of the bacterial community inhabiting marine estuarine sediments (salinity 31‰). The results showed that a single pulse of NM-300 AgNPs (1 mg L(-1)) that led to sediment concentrations below 6 mg Ag kg(-1) dry weight inhibited the bacterial utilization of environmentally relevant carbon substrates. As a result, the functional diversity changed, but recovered after 120 h under the experimental conditions. This microcosm study suggests that AgNPs under environmentally relevant experimental conditions can negatively affect bacterial function and provides an insight into the understanding of the bacterial community response and resilience to AgNPs exposure, important for informing relevant regulatory measures.

ACS Style

Virginia Echavarri-Bravo; Lynn Paterson; Thomas Aspray; Joanne S. Porter; Michael K. Winson; Barry Thornton; Mark G.J. Hartl. Shifts in the metabolic function of a benthic estuarine microbial community following a single pulse exposure to silver nanoparticles. Environmental Pollution 2015, 201, 91 -99.

AMA Style

Virginia Echavarri-Bravo, Lynn Paterson, Thomas Aspray, Joanne S. Porter, Michael K. Winson, Barry Thornton, Mark G.J. Hartl. Shifts in the metabolic function of a benthic estuarine microbial community following a single pulse exposure to silver nanoparticles. Environmental Pollution. 2015; 201 ():91-99.

Chicago/Turabian Style

Virginia Echavarri-Bravo; Lynn Paterson; Thomas Aspray; Joanne S. Porter; Michael K. Winson; Barry Thornton; Mark G.J. Hartl. 2015. "Shifts in the metabolic function of a benthic estuarine microbial community following a single pulse exposure to silver nanoparticles." Environmental Pollution 201, no. : 91-99.

Journal article
Published: 01 December 2014 in Environmental Pollution
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Bacteria based ecotoxicology assessment of manufactured nanoparticles is largely restricted to Escherichia coli bioreporters in laboratory media. Here, toxicity effects of model OECD nanoparticles (Ag NM-300K, ZnO NM-110 and TiO2 NM-104) were assessed using the switch-off luminescent Pseudomonas putida BS566::luxCDABE bioreporter in Luria Bertani (LB) medium and artificial wastewater (AW). IC50 values ∼4 mg L(-1), 100 mg L(-1) and >200 mg L(-1) at 1 h were observed in LB for Ag NM-300K, ZnO NM-110 and TiO2 NM-104, respectively. Similar results were obtained in AW for Ag NM-300K (IC50∼5 mg L(-1)) and TiO2 NM-104 (IC50>200 mg L(-1)) whereas ZnO NM-110 was significantly higher (IC50>200 mg L(-1)). Lower ZnO NM-110 toxicity in AW compared to LB was associated with differences in agglomeration status and dissolution rate. This work demonstrates the importance of nanoecotoxicological studies in environmentally relevant matrices.

ACS Style

Florian Mallevre; Teresa F. Fernandes; Thomas J. Aspray. Silver, zinc oxide and titanium dioxide nanoparticle ecotoxicity to bioluminescent Pseudomonas putida in laboratory medium and artificial wastewater. Environmental Pollution 2014, 195, 218 -225.

AMA Style

Florian Mallevre, Teresa F. Fernandes, Thomas J. Aspray. Silver, zinc oxide and titanium dioxide nanoparticle ecotoxicity to bioluminescent Pseudomonas putida in laboratory medium and artificial wastewater. Environmental Pollution. 2014; 195 ():218-225.

Chicago/Turabian Style

Florian Mallevre; Teresa F. Fernandes; Thomas J. Aspray. 2014. "Silver, zinc oxide and titanium dioxide nanoparticle ecotoxicity to bioluminescent Pseudomonas putida in laboratory medium and artificial wastewater." Environmental Pollution 195, no. : 218-225.

Journal article
Published: 23 May 2013 in Optics Express
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Two dimensional interferometric trapping of multiple microspheres and Escherichia coli has been demonstrated using a multicore fiber lensed with an electric arc fusion splicer. Light was coupled evenly into all four cores using a diffractive optical element. The visibility of the fringes and also the appearance of the lattice can be altered by rotating a half wave-plate. As a result the particles can be manipulated from one dimensional trapping to two dimensional trapping or a variety of different two dimensional arrangements. The ability to align bacterial populations has potential application for quorum sensing, floc and biofilm and, metabolic co-operation studies.

ACS Style

Ashleigh L. Barron; Ajoy Kar; Thomas Aspray; Andrew John Waddie; Mohammad Reza Taghizadeh; Henry T. Bookey. Two dimensional interferometric optical trapping of multiple particles and Escherichia coli bacterial cells using a lensed multicore fiber. Optics Express 2013, 21, 13199 -13207.

AMA Style

Ashleigh L. Barron, Ajoy Kar, Thomas Aspray, Andrew John Waddie, Mohammad Reza Taghizadeh, Henry T. Bookey. Two dimensional interferometric optical trapping of multiple particles and Escherichia coli bacterial cells using a lensed multicore fiber. Optics Express. 2013; 21 (11):13199-13207.

Chicago/Turabian Style

Ashleigh L. Barron; Ajoy Kar; Thomas Aspray; Andrew John Waddie; Mohammad Reza Taghizadeh; Henry T. Bookey. 2013. "Two dimensional interferometric optical trapping of multiple particles and Escherichia coli bacterial cells using a lensed multicore fiber." Optics Express 21, no. 11: 13199-13207.

Journal article
Published: 01 May 2013 in Environmental Pollution
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Multiple substrate induced respiration (MSIR) assays which assess the response of soils to carbon source amendment are effective approaches to determine catabolic diversity of soils. Many assays are based on a single short term (<6 h) time point measurement and usually limited to CO2 production only. However, repeated measurements of both CO2 and O2 simultaneously can provide additional valuable information. In this study, a MSIR assay involving eight carbon sources was applied to three hydrocarbon contaminated soils using continuous CO2 and O2 respiration measurements. Based on cumulative CO2 and O2 measurements at 4, 24 and 120 h, the soils were found to be distinct in terms of their catabolic diversity. Most noteworthy, however, was the response to the addition of maleic acid which provided strong evidence of abiotic CO2 efflux to be the overriding process, raising questions about the interpretation of CO2 only responses from organic acid addition in MSIR assays.

ACS Style

Stéphane Pietravalle; Thomas J. Aspray. CO2 and O2 respiration kinetics in hydrocarbon contaminated soils amended with organic carbon sources used to determine catabolic diversity. Environmental Pollution 2013, 176, 42 -47.

AMA Style

Stéphane Pietravalle, Thomas J. Aspray. CO2 and O2 respiration kinetics in hydrocarbon contaminated soils amended with organic carbon sources used to determine catabolic diversity. Environmental Pollution. 2013; 176 ():42-47.

Chicago/Turabian Style

Stéphane Pietravalle; Thomas J. Aspray. 2013. "CO2 and O2 respiration kinetics in hydrocarbon contaminated soils amended with organic carbon sources used to determine catabolic diversity." Environmental Pollution 176, no. : 42-47.

Original paper
Published: 09 February 2013 in Mycorrhiza
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Paenibacillus sp. EJP73 has been previously demonstrated as a mycorrhization helper bacterium (MHB) for the Lactarius rufus–Pinus sylvestris symbiosis in both laboratory and glasshouse experiments. In the present study, the effect of Paenibacillus sp. EJP73 metabolites on L. rufus EO3 pre-symbiotic growth was tested in two agar plate-based systems. Specifically, volatile metabolites were investigated using a dual plate system, in which the presence of strain EJP73 resulted in a significant negative effect on L. rufus EO3 hyphal radial growth but enhanced hyphal branching and reduced internode distance. Soluble metabolites produced by strain EJP73 were tested on L. rufus EO3 growth in single-agar plate assays by incorporating bacterial cell-free whole or molecular weight fraction spent broth into the agar. Whole spent broth had a negative effect on hyphal growth, whereas a low molecular weight fraction (100–1,000) promoted colony radial growth. Headspace and spent broth analysis of strain EJP73 cultures revealed 2,5-diisopropylpyrazine to be the most significant component. Synthesised 2,5-diisopropylpyrazine and elevated CO2 (2,000 ppm) were tested as specific volatile metabolites in the dual plate system, but neither produced the response shown when strain EJP73 was present. Increased pre-symbiotic hyphal branching leading to increased likelihood of plant infection may be an important MHB mechanism for strain EJP73. Although the precise signal molecules could not be identified, the work suggests a number of metabolites may work synergistically to increase L. rufus root colonisation.

ACS Style

T. J. Aspray; E. E. Jones; M. W. Davies; M. Shipman; G. D. Bending. Increased hyphal branching and growth of ectomycorrhizal fungus Lactarius rufus by the helper bacterium Paenibacillus sp. Mycorrhiza 2013, 23, 403 -410.

AMA Style

T. J. Aspray, E. E. Jones, M. W. Davies, M. Shipman, G. D. Bending. Increased hyphal branching and growth of ectomycorrhizal fungus Lactarius rufus by the helper bacterium Paenibacillus sp. Mycorrhiza. 2013; 23 (5):403-410.

Chicago/Turabian Style

T. J. Aspray; E. E. Jones; M. W. Davies; M. Shipman; G. D. Bending. 2013. "Increased hyphal branching and growth of ectomycorrhizal fungus Lactarius rufus by the helper bacterium Paenibacillus sp." Mycorrhiza 23, no. 5: 403-410.

Conference paper
Published: 01 January 2013 in Workshop on Specialty Optical Fibers and Their Applications
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A lensed multicore fiber trapping probe has been fabricated using a fusion splicer. One and two dimensional trapping has been demonstrated for particles and Escherichia coli using a DOE or a fully integrated fan-out device.

ACS Style

Ashleigh L. Barron; Ajoy Kar; Graeme Brown; Thomas Aspray; Andrew J. Waddie; Mohammad R. Taghizadeh; Henry T. Bookey. Optical Trapping using a Lensed Multicore Fiber. Workshop on Specialty Optical Fibers and Their Applications 2013, T1.3 .

AMA Style

Ashleigh L. Barron, Ajoy Kar, Graeme Brown, Thomas Aspray, Andrew J. Waddie, Mohammad R. Taghizadeh, Henry T. Bookey. Optical Trapping using a Lensed Multicore Fiber. Workshop on Specialty Optical Fibers and Their Applications. 2013; ():T1.3.

Chicago/Turabian Style

Ashleigh L. Barron; Ajoy Kar; Graeme Brown; Thomas Aspray; Andrew J. Waddie; Mohammad R. Taghizadeh; Henry T. Bookey. 2013. "Optical Trapping using a Lensed Multicore Fiber." Workshop on Specialty Optical Fibers and Their Applications , no. : T1.3.

Journal article
Published: 01 June 2012 in Journal of Hazardous Materials
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Soil washing is an ex situ soil remediation treatment process. The purpose of soil washing is to clean the major gravel and sand fractions, concentrating contamination into the fine silt and clay fractions. The addition of surfactants can improve the efficiency of this method. Here we report the use of UV fluorescence spectroscopy to assess the hydrocarbon cleaning process as a rapid and cost effective alternative to gas chromatography. Three wash solutions were tested on a total petroleum hydrocarbon contaminated soil: water, Sea Power 101 (SP101) at 1% (v/v) and Tween80 at 0.5% (w/v). The most effective to wash the gravel and sand was SP101 (54 and 65% improvement over the water only wash, respectively) which moved contamination to the silt fraction (94% of contaminants). Tween80 appeared not to enhance TPH removal efficiency from the gravel and sand fractions but did concentrate TPH in the effluent (95% more than water wash). In addition to TPH removal from gravel and sand, SP101 also showed potential benefit in the soil washing sedimentation process, enhancing sludge/water volume separation by 10% over the water only wash. In summary, fluorescence spectroscopy proved an effective technique to compare TPH removal efficiencies as part of soil washing laboratory based treatability testing.

ACS Style

Amandine Uhmann; Thomas Aspray. Potential benefit of surfactants in a hydrocarbon contaminated soil washing process: Fluorescence spectroscopy based assessment. Journal of Hazardous Materials 2012, 219-220, 141 -147.

AMA Style

Amandine Uhmann, Thomas Aspray. Potential benefit of surfactants in a hydrocarbon contaminated soil washing process: Fluorescence spectroscopy based assessment. Journal of Hazardous Materials. 2012; 219-220 ():141-147.

Chicago/Turabian Style

Amandine Uhmann; Thomas Aspray. 2012. "Potential benefit of surfactants in a hydrocarbon contaminated soil washing process: Fluorescence spectroscopy based assessment." Journal of Hazardous Materials 219-220, no. : 141-147.

Journal article
Published: 30 September 2010 in International Biodeterioration & Biodegradation
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ACS Style

A. Sakultantimetha; H.E. Keenan; T.K. Beattie; T.J. Aspray; S. Bangkedphol; A. Songsasen. Acceleration of tributyltin biodegradation by sediment microorganisms under optimized environmental conditions. International Biodeterioration & Biodegradation 2010, 64, 467 -473.

AMA Style

A. Sakultantimetha, H.E. Keenan, T.K. Beattie, T.J. Aspray, S. Bangkedphol, A. Songsasen. Acceleration of tributyltin biodegradation by sediment microorganisms under optimized environmental conditions. International Biodeterioration & Biodegradation. 2010; 64 (6):467-473.

Chicago/Turabian Style

A. Sakultantimetha; H.E. Keenan; T.K. Beattie; T.J. Aspray; S. Bangkedphol; A. Songsasen. 2010. "Acceleration of tributyltin biodegradation by sediment microorganisms under optimized environmental conditions." International Biodeterioration & Biodegradation 64, no. 6: 467-473.

Journal article
Published: 31 January 2010 in Soil Biology and Biochemistry
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Mecoprop-p [(R)-2-(4-chloro-2-methylphenoxy) propanoic acid) is widely used in agriculture and poses an environmental concern because of its susceptibility to leach from soil to water. We investigated the effect of soil depth on mecoprop-p biodegradation and its relationship with the number and diversity of tfdA related genes, which are the most widely known genes involved in degradation of the phenoxyalkanoic acid group of herbicides by bacteria. Mecoprop-p half-life (DT50) was approximately 12 days in soil sampled from <30 cm depth, and increased progressively with soil depth, reaching over 84 days at 70–80 cm. In sub-soil there was a lag period of between 23 and 34 days prior to a phase of rapid degradation. No lag phase occurred in top-soil samples prior to the onset of degradation. The maximum degradation rate was the same in top-soil and sub-soil samples. Although diverse tfdAα and tfdA genes were present prior to mecoprop-p degradation, real time PCR revealed that degradation was associated with proliferation of tfdA genes. The number of tfdA genes and the most probable number of mecoprop-p degrading organisms in soil prior to mecoprop-p addition were below the limit of quantification and detection respectively. Melting curves from the real time PCR analysis showed that prior to mecoprop-p degradation both class I and class III tfdA genes were present in top- and sub-soil samples. However at all soil depths only tfdA class III genes proliferated during degradation. Denaturing gradient gel electrophoresis confirmed that class III tfdA genes were associated with mecoprop-p degradation. Degradation was not associated with the induction of novel tfdA genes in top- or sub-soil samples, and there were no apparent differences in tfdA gene diversity with soil depth prior to or following degradation.

ACS Style

M Sonia Rodríguez-Cruz; Jacob Bælum; Liz J. Shaw; Sebastian R. Sørensen; Shengjing Shi; Thomas Aspray; Carsten S. Jacobsen; Gary D. Bending. Biodegradation of the herbicide mecoprop-p with soil depth and its relationship with class III tfdA genes. Soil Biology and Biochemistry 2010, 42, 32 -39.

AMA Style

M Sonia Rodríguez-Cruz, Jacob Bælum, Liz J. Shaw, Sebastian R. Sørensen, Shengjing Shi, Thomas Aspray, Carsten S. Jacobsen, Gary D. Bending. Biodegradation of the herbicide mecoprop-p with soil depth and its relationship with class III tfdA genes. Soil Biology and Biochemistry. 2010; 42 (1):32-39.

Chicago/Turabian Style

M Sonia Rodríguez-Cruz; Jacob Bælum; Liz J. Shaw; Sebastian R. Sørensen; Shengjing Shi; Thomas Aspray; Carsten S. Jacobsen; Gary D. Bending. 2010. "Biodegradation of the herbicide mecoprop-p with soil depth and its relationship with class III tfdA genes." Soil Biology and Biochemistry 42, no. 1: 32-39.