Ceri Gwyther - Academia.edu (original) (raw)

Papers by Ceri Gwyther

Applied microbiology: open access, Nov 7, 2017

Journal of Environmental Management, 2020

Intensive farming is widespread throughout the UK and yet the health effects of bioaerosols which... more Intensive farming is widespread throughout the UK and yet the health effects of bioaerosols which may be generated by these sites are currently not well researched. A scoping study was established to measure bioaerosols emitted from intensive pig (n = 3) and poultry farms (n = 3) during the period 2014-2015. The concentration of culturable mesophilic bacteria, Gramnegative bacteria, Staphylococcus spp., and fungi selecting for presumptive Aspergillus fumigatus were measured using single-stage impaction Andersen samplers, whilst endotoxin and (1→3)-β-D-glucan was undertaken using inhalable personal samplers. Particulate matter concentration was determined using an optical particulate monitor. Results showed that culturable bacteria, fungi, presumptive Staphylococcus aureus (confirmed only as Staphylococcus spp.) and endotoxin concentrations were elevated above background concentrations for distances of up to 250 m downwind of the source. Of all the culturable bioaerosols measured, bacteria and Staphylococcus spp. were identified as the most significant, exceeding published or proposed bioaerosol guidelines in the UK. In particular, culturable Staphylococcus spp. downwind was at least 61 times higher than background at the boundary and at least 8 times higher 70m downwind on the four farms tested. This research represents a novel dataset of intensive farm emissions within the UK. Future research should exploit the use of innovative culture-independent methods such as next generation sequencing to develop deeper insights into the make-up of microbial communities emitted from intensive farming facilities and which would better inform species of interest from a public health perspective.

Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populat... more Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populations. To date, most research focused on occupational exposure, whilst much less is known about the impact of emissions from industrial operations on downwind endotoxin concentrations. A review of the literature was undertaken, identifying studies that reported endotoxin concentrations in both ambient environments and around sources with high endotoxin emissions. Ambient endotoxin concentrations in both rural and urban areas are generally below 10 endotoxin units (EU) m−3; however, around significant sources such as compost facilities, farms, and wastewater treatment plants, endotoxin concentrations regularly exceeded 100 EU m−3. However, this is affected by a range of factors including sampling approach, equipment, and duration. Reported downwind measurements of endotoxin demonstrate that endotoxin concentrations can remain above upwind concentrations. The evaluation of reported data is ...

Bioreduction has been proposed as an on-farm storage facility for fallen stock prior to final dis... more Bioreduction has been proposed as an on-farm storage facility for fallen stock prior to final disposal in accordance with the Animal By-Products Regulations, ABPR (EC 1069/2009). In order for bioreduction to be approved under the legislation it must be shown to be biosecure. Therefore, the main aim of this thesis was to assess the risk of pathogen proliferation in the liquor and bioaerosols generated under operational and simulated breakdown scenarios. Secondary objectives consisted of improving the technology and included: determining the efficacy of commercial accelerants in catalysing the bioreduction process; the use of the carbon footprint to identify potential environmental improvements in future vessel designs; and identifying the main physicochemical parameters and enzyme activity associated with bioreduction, in order to more fully understand the underlying biodegradation processes occurring within the vessels. A range of microbiological and molecular techniques were employ...

Atmosphere

Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populat... more Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populations. To date, most research focused on occupational exposure, whilst much less is known about the impact of emissions from industrial operations on downwind endotoxin concentrations. A review of the literature was undertaken, identifying studies that reported endotoxin concentrations in both ambient environments and around sources with high endotoxin emissions. Ambient endotoxin concentrations in both rural and urban areas are generally below 10 endotoxin units (EU) m−3; however, around significant sources such as compost facilities, farms, and wastewater treatment plants, endotoxin concentrations regularly exceeded 100 EU m−3. However, this is affected by a range of factors including sampling approach, equipment, and duration. Reported downwind measurements of endotoxin demonstrate that endotoxin concentrations can remain above upwind concentrations. The evaluation of reported data is ...

Science of The Total Environment

A study of the potential release of bioaerosols from containers as a result of reduced frequency ... more A study of the potential release of bioaerosols from containers as a result of reduced frequency residual waste collections. Science of the Total Environment, 576 pp. 481-489. For guidance on citations see FAQs.

Frontiers in Microbiology, 2016

viral/bacterial-sediment interactions combined with methodological challenges is limiting the acc... more viral/bacterial-sediment interactions combined with methodological challenges is limiting the accurate source apportionment and quantitative microbial risk assessment for pathogenic organisms associated with sediments in aquatic environments.

Waste Management, 2012

The EU Animal By-Products Regulations generated the need for novel methods of storage and disposa... more The EU Animal By-Products Regulations generated the need for novel methods of storage and disposal of dead livestock. Bioreduction prior to rendering or incineration has been proposed as a practical and potentially cost-effective method; however, its biosecurity characteristics need to be elucidated. To address this, Salmonella enterica (serovars Senftenberg and Poona), Enterococcus faecalis, Campylobacter jejuni, Campylobacter coli and a lux-marked strain of Escherichia coli O157 were inoculated into laboratory-scale bioreduction vessels containing sheep carcass constituents. Numbers of all pathogens and the metabolic activity of E. coli O157 decreased significantly within the liquor waste over time, and only E. faecalis remained detectable after three months. Only very low numbers of Salmonella spp. and E. faecalis were detected in bioaerosols, and only at initial stages of the trial. These results further indicate that bioreduction represents a suitable method of storing and reducing the volume of livestock carcasses prior to ultimate disposal.

Waste Management, 2011

Livestock mortalities represent a major waste stream within agriculture. Many different methods a... more Livestock mortalities represent a major waste stream within agriculture. Many different methods are used throughout the world to dispose of these mortalities; however within the European Union (EU) disposal options are limited by stringent legislation. The legal disposal options currently available to EU farmers (primarily rendering and incineration) are frequently negatively perceived on both practical and economic grounds. In this review, we assess the potential environment impacts and biosecurity risks associated with each of the main options used for disposal of livestock mortalities in the world and critically evaluate the justification for current EU regulations. Overall, we conclude that while current legislation intends to minimise the potential for on-farm pollution and the spread of infectious diseases (e.g. Transmissible Spongiform Encephalopathies, bacterial pathogens), alternative technologies (e.g. bioreduction, anaerobic digestion) may provide a more cost-effective, practical and biosecure mechanism for carcass disposal as well as having a lower environmental footprint. Further social, environmental and economic research is therefore warranted to assess the holistic benefits of alternative approaches for carcass disposal in Europe, with an aim to provide policy-makers with robust knowledge to make informed decisions on future legislation.

Environmental Technology, 2014

Bioreduction is a novel method for the on-farm storage of fallen stock in a vessel containing wat... more Bioreduction is a novel method for the on-farm storage of fallen stock in a vessel containing water that is heated and aerated, prior to disposal. The combination of a mesophilic temperature and high bacterial population leads to rapid degradation of carcasses due to microbial and enzymatic breakdown of protein material; and ultimately the reduction in volume of waste to be disposed. The system could, however, be improved if more was known about the changes that occur during a bioreduction cycle. Pig carcasses were placed within two commercial-scale bioreduction vessels (BVs) (6.5 m3 capacity) and the changes in physicochemical parameters, enzymatic activity, gas emissions and microbial communities were analysed over 56 days. Analyses showed that each vessel displayed different physicochemical parameters. The microbial communities within both vessels were also distinct, though they converged between days 28 and 42 before again diverging. Of the enzymes assayed, acetylesterases showed the highest activity during initial stages, with a subsequent increase in lipase towards the end. All other enzymes showed little activity in comparison. Despite active aeration of the vessels, conditions were redox-constrained, leading to the emission of gases associated with anaerobic conditions, namely NH3 and H2S. It was concluded that no single parameter governed the biochemical processes and that each BV will have its own unique microbial population and hence rate of decomposition. Further work is needed to increase the rate of bioreduction through bioaugmentation or developing enzyme additives.

Environmental Science & Technology, 2013

Options for the storage and disposal of animal carcasses are extremely limited in the EU after th... more Options for the storage and disposal of animal carcasses are extremely limited in the EU after the introduction of the EU Animal By-products Regulations (ABPR; EC/1774/2002), leading to animosity within the livestock sector and the call for alternative methods to be validated. Novel storage technologies such as bioreduction may be approved under the ABPR provided that they can be shown to prevent pathogen proliferation. We studied the survival of Enterococcus faecalis, Salmonella spp., E. coli O157 and porcine parvovirus in bioreduction vessels containing sheep carcasses for approximately 4 months. The vessels were operated under two different scenarios: (A) where the water within was aerated and heated to 40°C, and (B) with no aeration or heating, to simulate vessel failure. Microbial analysis verified that pathogens were contained within the bioreduction vessel and indeed reduced in numbers with time under both scenarios. This study shows that bioreduction can provide an effective and safe on-farm storage system for livestock carcasses prior to ultimate disposal. The findings support a review of the current regulatory framework so that bioreduction is considered for approval for industry use within the EU. ■ MATERIALS AND METHODS Bioreduction Vessel Design and Location. Three 6,500 L capacity bioreduction vessels (BVs) made of high-density polymer and thermostable glass fiber were commissioned at

Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populat... more Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populations. To date, most research focused on occupational exposure, whilst much less is known about the impact of emissions from industrial operations on downwind endotoxin concentrations. A review of the literature was undertaken, identifying studies that reported endotoxin concentrations in both ambient environments and around sources with high endotoxin emissions. Ambient endotoxin concentrations in both rural and urban areas are generally below 10 endotoxin units (EU) m −3 ; however, around significant sources such as compost facilities, farms, and wastewater treatment plants, endotoxin concentrations regularly exceeded 100 EU m −3. However, this is affected by a range of factors including sampling approach, equipment, and duration. Reported downwind measurements of endotoxin demonstrate that endotoxin concentrations can remain above upwind concentrations. The evaluation of reported data is complicated due to a wide range of different parameters including sampling approaches, temperature, and site activity, demonstrating the need for a standardised methodology and improved guidance. Thorough characterisation of ambient endotoxin levels and modelling of endotoxin from pollution sources is needed to help inform future policy and support a robust health-based risk assessment process.

Atmosphere

Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populat... more Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populations. To date, most research focused on occupational exposure, whilst much less is known about the impact of emissions from industrial operations on downwind endotoxin concentrations. A review of the literature was undertaken, identifying studies that reported endotoxin concentrations in both ambient environments and around sources with high endotoxin emissions. Ambient endotoxin concentrations in both rural and urban areas are generally below 10 endotoxin units (EU) m−3; however, around significant sources such as compost facilities, farms, and wastewater treatment plants, endotoxin concentrations regularly exceeded 100 EU m−3. However, this is affected by a range of factors including sampling approach, equipment, and duration. Reported downwind measurements of endotoxin demonstrate that endotoxin concentrations can remain above upwind concentrations. The evaluation of reported data is ...

Applied microbiology: open access, Nov 7, 2017

Journal of Environmental Management, 2020

Intensive farming is widespread throughout the UK and yet the health effects of bioaerosols which... more Intensive farming is widespread throughout the UK and yet the health effects of bioaerosols which may be generated by these sites are currently not well researched. A scoping study was established to measure bioaerosols emitted from intensive pig (n = 3) and poultry farms (n = 3) during the period 2014-2015. The concentration of culturable mesophilic bacteria, Gramnegative bacteria, Staphylococcus spp., and fungi selecting for presumptive Aspergillus fumigatus were measured using single-stage impaction Andersen samplers, whilst endotoxin and (1→3)-β-D-glucan was undertaken using inhalable personal samplers. Particulate matter concentration was determined using an optical particulate monitor. Results showed that culturable bacteria, fungi, presumptive Staphylococcus aureus (confirmed only as Staphylococcus spp.) and endotoxin concentrations were elevated above background concentrations for distances of up to 250 m downwind of the source. Of all the culturable bioaerosols measured, bacteria and Staphylococcus spp. were identified as the most significant, exceeding published or proposed bioaerosol guidelines in the UK. In particular, culturable Staphylococcus spp. downwind was at least 61 times higher than background at the boundary and at least 8 times higher 70m downwind on the four farms tested. This research represents a novel dataset of intensive farm emissions within the UK. Future research should exploit the use of innovative culture-independent methods such as next generation sequencing to develop deeper insights into the make-up of microbial communities emitted from intensive farming facilities and which would better inform species of interest from a public health perspective.

Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populat... more Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populations. To date, most research focused on occupational exposure, whilst much less is known about the impact of emissions from industrial operations on downwind endotoxin concentrations. A review of the literature was undertaken, identifying studies that reported endotoxin concentrations in both ambient environments and around sources with high endotoxin emissions. Ambient endotoxin concentrations in both rural and urban areas are generally below 10 endotoxin units (EU) m−3; however, around significant sources such as compost facilities, farms, and wastewater treatment plants, endotoxin concentrations regularly exceeded 100 EU m−3. However, this is affected by a range of factors including sampling approach, equipment, and duration. Reported downwind measurements of endotoxin demonstrate that endotoxin concentrations can remain above upwind concentrations. The evaluation of reported data is ...

Bioreduction has been proposed as an on-farm storage facility for fallen stock prior to final dis... more Bioreduction has been proposed as an on-farm storage facility for fallen stock prior to final disposal in accordance with the Animal By-Products Regulations, ABPR (EC 1069/2009). In order for bioreduction to be approved under the legislation it must be shown to be biosecure. Therefore, the main aim of this thesis was to assess the risk of pathogen proliferation in the liquor and bioaerosols generated under operational and simulated breakdown scenarios. Secondary objectives consisted of improving the technology and included: determining the efficacy of commercial accelerants in catalysing the bioreduction process; the use of the carbon footprint to identify potential environmental improvements in future vessel designs; and identifying the main physicochemical parameters and enzyme activity associated with bioreduction, in order to more fully understand the underlying biodegradation processes occurring within the vessels. A range of microbiological and molecular techniques were employ...

Atmosphere

Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populat... more Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populations. To date, most research focused on occupational exposure, whilst much less is known about the impact of emissions from industrial operations on downwind endotoxin concentrations. A review of the literature was undertaken, identifying studies that reported endotoxin concentrations in both ambient environments and around sources with high endotoxin emissions. Ambient endotoxin concentrations in both rural and urban areas are generally below 10 endotoxin units (EU) m−3; however, around significant sources such as compost facilities, farms, and wastewater treatment plants, endotoxin concentrations regularly exceeded 100 EU m−3. However, this is affected by a range of factors including sampling approach, equipment, and duration. Reported downwind measurements of endotoxin demonstrate that endotoxin concentrations can remain above upwind concentrations. The evaluation of reported data is ...

Science of The Total Environment

A study of the potential release of bioaerosols from containers as a result of reduced frequency ... more A study of the potential release of bioaerosols from containers as a result of reduced frequency residual waste collections. Science of the Total Environment, 576 pp. 481-489. For guidance on citations see FAQs.

Frontiers in Microbiology, 2016

viral/bacterial-sediment interactions combined with methodological challenges is limiting the acc... more viral/bacterial-sediment interactions combined with methodological challenges is limiting the accurate source apportionment and quantitative microbial risk assessment for pathogenic organisms associated with sediments in aquatic environments.

Waste Management, 2012

The EU Animal By-Products Regulations generated the need for novel methods of storage and disposa... more The EU Animal By-Products Regulations generated the need for novel methods of storage and disposal of dead livestock. Bioreduction prior to rendering or incineration has been proposed as a practical and potentially cost-effective method; however, its biosecurity characteristics need to be elucidated. To address this, Salmonella enterica (serovars Senftenberg and Poona), Enterococcus faecalis, Campylobacter jejuni, Campylobacter coli and a lux-marked strain of Escherichia coli O157 were inoculated into laboratory-scale bioreduction vessels containing sheep carcass constituents. Numbers of all pathogens and the metabolic activity of E. coli O157 decreased significantly within the liquor waste over time, and only E. faecalis remained detectable after three months. Only very low numbers of Salmonella spp. and E. faecalis were detected in bioaerosols, and only at initial stages of the trial. These results further indicate that bioreduction represents a suitable method of storing and reducing the volume of livestock carcasses prior to ultimate disposal.

Waste Management, 2011

Livestock mortalities represent a major waste stream within agriculture. Many different methods a... more Livestock mortalities represent a major waste stream within agriculture. Many different methods are used throughout the world to dispose of these mortalities; however within the European Union (EU) disposal options are limited by stringent legislation. The legal disposal options currently available to EU farmers (primarily rendering and incineration) are frequently negatively perceived on both practical and economic grounds. In this review, we assess the potential environment impacts and biosecurity risks associated with each of the main options used for disposal of livestock mortalities in the world and critically evaluate the justification for current EU regulations. Overall, we conclude that while current legislation intends to minimise the potential for on-farm pollution and the spread of infectious diseases (e.g. Transmissible Spongiform Encephalopathies, bacterial pathogens), alternative technologies (e.g. bioreduction, anaerobic digestion) may provide a more cost-effective, practical and biosecure mechanism for carcass disposal as well as having a lower environmental footprint. Further social, environmental and economic research is therefore warranted to assess the holistic benefits of alternative approaches for carcass disposal in Europe, with an aim to provide policy-makers with robust knowledge to make informed decisions on future legislation.

Environmental Technology, 2014

Bioreduction is a novel method for the on-farm storage of fallen stock in a vessel containing wat... more Bioreduction is a novel method for the on-farm storage of fallen stock in a vessel containing water that is heated and aerated, prior to disposal. The combination of a mesophilic temperature and high bacterial population leads to rapid degradation of carcasses due to microbial and enzymatic breakdown of protein material; and ultimately the reduction in volume of waste to be disposed. The system could, however, be improved if more was known about the changes that occur during a bioreduction cycle. Pig carcasses were placed within two commercial-scale bioreduction vessels (BVs) (6.5 m3 capacity) and the changes in physicochemical parameters, enzymatic activity, gas emissions and microbial communities were analysed over 56 days. Analyses showed that each vessel displayed different physicochemical parameters. The microbial communities within both vessels were also distinct, though they converged between days 28 and 42 before again diverging. Of the enzymes assayed, acetylesterases showed the highest activity during initial stages, with a subsequent increase in lipase towards the end. All other enzymes showed little activity in comparison. Despite active aeration of the vessels, conditions were redox-constrained, leading to the emission of gases associated with anaerobic conditions, namely NH3 and H2S. It was concluded that no single parameter governed the biochemical processes and that each BV will have its own unique microbial population and hence rate of decomposition. Further work is needed to increase the rate of bioreduction through bioaugmentation or developing enzyme additives.

Environmental Science & Technology, 2013

Options for the storage and disposal of animal carcasses are extremely limited in the EU after th... more Options for the storage and disposal of animal carcasses are extremely limited in the EU after the introduction of the EU Animal By-products Regulations (ABPR; EC/1774/2002), leading to animosity within the livestock sector and the call for alternative methods to be validated. Novel storage technologies such as bioreduction may be approved under the ABPR provided that they can be shown to prevent pathogen proliferation. We studied the survival of Enterococcus faecalis, Salmonella spp., E. coli O157 and porcine parvovirus in bioreduction vessels containing sheep carcasses for approximately 4 months. The vessels were operated under two different scenarios: (A) where the water within was aerated and heated to 40°C, and (B) with no aeration or heating, to simulate vessel failure. Microbial analysis verified that pathogens were contained within the bioreduction vessel and indeed reduced in numbers with time under both scenarios. This study shows that bioreduction can provide an effective and safe on-farm storage system for livestock carcasses prior to ultimate disposal. The findings support a review of the current regulatory framework so that bioreduction is considered for approval for industry use within the EU. ■ MATERIALS AND METHODS Bioreduction Vessel Design and Location. Three 6,500 L capacity bioreduction vessels (BVs) made of high-density polymer and thermostable glass fiber were commissioned at

Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populat... more Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populations. To date, most research focused on occupational exposure, whilst much less is known about the impact of emissions from industrial operations on downwind endotoxin concentrations. A review of the literature was undertaken, identifying studies that reported endotoxin concentrations in both ambient environments and around sources with high endotoxin emissions. Ambient endotoxin concentrations in both rural and urban areas are generally below 10 endotoxin units (EU) m −3 ; however, around significant sources such as compost facilities, farms, and wastewater treatment plants, endotoxin concentrations regularly exceeded 100 EU m −3. However, this is affected by a range of factors including sampling approach, equipment, and duration. Reported downwind measurements of endotoxin demonstrate that endotoxin concentrations can remain above upwind concentrations. The evaluation of reported data is complicated due to a wide range of different parameters including sampling approaches, temperature, and site activity, demonstrating the need for a standardised methodology and improved guidance. Thorough characterisation of ambient endotoxin levels and modelling of endotoxin from pollution sources is needed to help inform future policy and support a robust health-based risk assessment process.

Atmosphere

Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populat... more Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populations. To date, most research focused on occupational exposure, whilst much less is known about the impact of emissions from industrial operations on downwind endotoxin concentrations. A review of the literature was undertaken, identifying studies that reported endotoxin concentrations in both ambient environments and around sources with high endotoxin emissions. Ambient endotoxin concentrations in both rural and urban areas are generally below 10 endotoxin units (EU) m−3; however, around significant sources such as compost facilities, farms, and wastewater treatment plants, endotoxin concentrations regularly exceeded 100 EU m−3. However, this is affected by a range of factors including sampling approach, equipment, and duration. Reported downwind measurements of endotoxin demonstrate that endotoxin concentrations can remain above upwind concentrations. The evaluation of reported data is ...