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Since conventional drinking water treatments applied in different countries are inefficient at eliminating potentially toxic cyanobacterial peptides, a number of bacteria have been studied as an alternative to biological filters for the removal of microcystins (MCs). Here, we evaluated the degradation of not only MCs variants (-LR/DM-LR/-RR/-LF/-YR), but also non-MCs peptides (anabaenopeptins A/B, aerucyclamides A/D) by Paucibacter toxinivorans over 7 days. We also evaluated the degradation rate of MC-LR in a peptide mix, with all peptides tested, and in the presence of M. aeruginosa crude extract. Furthermore, biodegradation was assessed for non-cyanobacterial peptides with different chemical structures, such as cyclosporin A, (Glu1)-fibrinopeptide-B, leucine-enkephalin, and oxytocin. When cyanopeptides were individually added, P. toxinivorans degraded them (99%) over 7 days, except for MC-LR and -RR, which decreased by about 85 and 90%, respectively. The degradation rate of MC-LR decreased in the peptide mix compared to an individual compound, however, in the presence of the Microcystis extract, it was degraded considerably faster (3 days). It was noted that biodegradation rates decreased in the mix for all MCs while non-MCs peptides were immediately degraded. UPLC–QTOF–MS/MS allowed us to identify two linear biodegradation products for MC-LR and MC-YR, and one for MC-LF. Furthermore, P. toxinivorans demonstrated complete degradation of non-cyanobacterial peptides, with the exception of oxytocin, where around 50% remained after 7 days. Thus, although P. toxinivorans was previously identified as a MC-degrader, it also degrades a wide range of peptides under a range of conditions, which could be optimized as a potential biological tool for water treatment.
Allan Santos; Sylvia Soldatou; Valeria de Magalhães; Sandra Azevedo; Dolores Camacho-Muñoz; Linda Lawton; Christine Edwards. Degradation of Multiple Peptides by Microcystin-Degrader Paucibacter toxinivorans (2C20). Toxins 2021, 13, 265 .
AMA StyleAllan Santos, Sylvia Soldatou, Valeria de Magalhães, Sandra Azevedo, Dolores Camacho-Muñoz, Linda Lawton, Christine Edwards. Degradation of Multiple Peptides by Microcystin-Degrader Paucibacter toxinivorans (2C20). Toxins. 2021; 13 (4):265.
Chicago/Turabian StyleAllan Santos; Sylvia Soldatou; Valeria de Magalhães; Sandra Azevedo; Dolores Camacho-Muñoz; Linda Lawton; Christine Edwards. 2021. "Degradation of Multiple Peptides by Microcystin-Degrader Paucibacter toxinivorans (2C20)." Toxins 13, no. 4: 265.
The presence of harmful algal bloom in many reservoirs around the world, alongside the lack of sanitation law/ordinance regarding cyanotoxin monitoring (particularly in developing countries), create a scenario in which the local population could potentially chronically consume cyanotoxin-contaminated waters. Therefore, it is crucial to develop low cost tools to detect possible systems failures and consequent toxin release inferred by morphological changes of cyanobacteria in the raw water. This paper aimed to look for the best combination of convolutional neural network (CNN), optimizer and image segmentation technique to differentiate P. agardhii trichomes before and after chemical stress caused by the addition of hydrogen peroxide. This method takes a step towards accurate monitoring of cyanobacteria in the field without the need for a mobile lab. After testing three different network architectures (AlexNet, 3ConvLayer and 2ConvLayer), four different optimizers (Adam, Adagrad, RMSProp and SDG) and five different image segmentations methods (Canny Edge Detection, Morphological Filter, HP filter, GrabCut and Watershed), the combination 2ConvLayer with Adam optimizer and GrabCut segmentation, provided the highest median accuracy (93.33%) for identifying H2O2-induced morphological changes in P. agardhii. Our results emphasize the fact that the trichome classification problem can be adequately tackled with a limited number of learned features due to the lack of complexity in micrographs from before and after chemical stress. To the authors knowledge, this is the first time that CNNs were applied to detect morphological changes in cyanobacteria caused by chemical stress. Thus, it is a significant step forward in developing low cost tools based on image recognition, to shield water consumers, especially in the poorest regions, against cyanotoxin-contaminated water.
Ismael Carloto; Pamela Johnston; Carlos J. Pestana; Linda A. Lawton. Detection of morphological changes caused by chemical stress in the cyanobacterium Planktothrix agardhii using convolutional neural networks. Science of The Total Environment 2021, 784, 146956 .
AMA StyleIsmael Carloto, Pamela Johnston, Carlos J. Pestana, Linda A. Lawton. Detection of morphological changes caused by chemical stress in the cyanobacterium Planktothrix agardhii using convolutional neural networks. Science of The Total Environment. 2021; 784 ():146956.
Chicago/Turabian StyleIsmael Carloto; Pamela Johnston; Carlos J. Pestana; Linda A. Lawton. 2021. "Detection of morphological changes caused by chemical stress in the cyanobacterium Planktothrix agardhii using convolutional neural networks." Science of The Total Environment 784, no. : 146956.
In the past twenty years marine biotoxin analysis in routine regulatory monitoring has advanced significantly in Europe (EU) and other regions from the use of the mouse bioassay (MBA) towards the high-end analytical techniques such as high-performance liquid chromatography (HPLC) with tandem mass spectrometry (MS). Previously, acceptance of these advanced methods, in progressing away from the MBA, was hindered by a lack of commercial certified analytical standards for method development and validation. This has now been addressed whereby the availability of a wide range of analytical standards from several companies in the EU, North America and Asia has enhanced the development and validation of methods to the required regulatory standards. However, the cost of the high-end analytical equipment, lengthy procedures and the need for qualified personnel to perform analysis can still be a challenge for routine monitoring laboratories. In developing regions, aquaculture production is increasing and alternative inexpensive Sensitive, Measurable, Accurate and Real-Time (SMART) rapid point-of-site testing (POST) methods suitable for novice end users that can be validated and internationally accepted remain an objective for both regulators and the industry. The range of commercial testing kits on the market for marine toxin analysis remains limited and even more so those meeting the requirements for use in regulatory control. Individual assays include enzyme-linked immunosorbent assays (ELISA) and lateral flow membrane-based immunoassays (LFIA) for EU-regulated toxins, such as okadaic acid (OA) and dinophysistoxins (DTXs), saxitoxin (STX) and its analogues and domoic acid (DA) in the form of three separate tests offering varying costs and benefits for the industry. It can be observed from the literature that not only are developments and improvements ongoing for these assays, but there are also novel assays being developed using upcoming state-of-the-art biosensor technology. This review focuses on both currently available methods and recent advances in innovative methods for marine biotoxin testing and the end-user practicalities that need to be observed. Furthermore, it highlights trends that are influencing assay developments such as multiplexing capabilities and rapid POST, indicating potential detection methods that will shape the future market.
Michael Dillon; Maja Zaczek-Moczydlowska; Christine Edwards; Andrew Turner; Peter Miller; Heather Moore; April McKinney; Linda Lawton; Katrina Campbell. Current Trends and Challenges for Rapid SMART Diagnostics at Point-of-Site Testing for Marine Toxins. Sensors 2021, 21, 2499 .
AMA StyleMichael Dillon, Maja Zaczek-Moczydlowska, Christine Edwards, Andrew Turner, Peter Miller, Heather Moore, April McKinney, Linda Lawton, Katrina Campbell. Current Trends and Challenges for Rapid SMART Diagnostics at Point-of-Site Testing for Marine Toxins. Sensors. 2021; 21 (7):2499.
Chicago/Turabian StyleMichael Dillon; Maja Zaczek-Moczydlowska; Christine Edwards; Andrew Turner; Peter Miller; Heather Moore; April McKinney; Linda Lawton; Katrina Campbell. 2021. "Current Trends and Challenges for Rapid SMART Diagnostics at Point-of-Site Testing for Marine Toxins." Sensors 21, no. 7: 2499.
Cyanobacterial blooms are increasingly reported worldwide, presenting a challenge to water treatment plants and concerning risks to human health and aquatic ecosystems. Advanced oxidative processes comprise efficient and safe methods for water treatment. Hydrogen peroxide (H2O2) has been proposed as a sustainable solution to mitigate bloom-forming cyanobacteria since this group presents a higher sensitivity compared to other phytoplankton, with no major risks to the environment at low concentrations. Here, we evaluated the effects of a single H2O2 addition (10 mg L−1) over 120 h in mesocosms introduced in a reservoir located in a semi-arid region presenting a Planktothrix-dominated cyanobacterial bloom. We followed changes in physical and chemical parameters and in the bacterioplankton composition. H2O2 efficiently suppressed cyanobacteria, green algae, and diatoms over 72 h, leading to an increase in transparency and dissolved organic carbon, and a decrease in dissolved oxygen and pH, while nutrient concentrations were not affected. After 120 h, cyanobacterial abundance remained low and green algae became dominant. 16S rRNA sequencing revealed that the original cyanobacterial bloom was composed by Planktothrix, Cyanobium and Microcystis. Only Cyanobium increased in relative abundance at 120 h, suggesting regrowth. A prominent change in the composition of heterotrophic bacteria was observed with Exiguobacterium, Paracoccus and Deinococcus becoming the most abundant genera after the H2O2 treatment. Our results indicate that this approach is efficient in suppressing cyanobacterial blooms and improving water quality in tropical environments. Monitoring changes in abiotic parameters and the relative abundance of specific bacterial taxa could be used to anticipate the regrowth of cyanobacteria after H2O2 degradation and to indicate where in the reservoir H2O2 should be applied so the effects are still felt in the water treatment plant intake.
Allan A. Santos; Dayvson O. Guedes; Mário U.G. Barros; Samylla Oliveira; Ana B.F. Pacheco; Sandra M.F.O. Azevedo; Valéria F. Magalhães; Carlos J. Pestana; Christine Edwards; Linda A. Lawton; José Capelo-Neto. Effect of hydrogen peroxide on natural phytoplankton and bacterioplankton in a drinking water reservoir: Mesocosm-scale study. Water Research 2021, 197, 117069 .
AMA StyleAllan A. Santos, Dayvson O. Guedes, Mário U.G. Barros, Samylla Oliveira, Ana B.F. Pacheco, Sandra M.F.O. Azevedo, Valéria F. Magalhães, Carlos J. Pestana, Christine Edwards, Linda A. Lawton, José Capelo-Neto. Effect of hydrogen peroxide on natural phytoplankton and bacterioplankton in a drinking water reservoir: Mesocosm-scale study. Water Research. 2021; 197 ():117069.
Chicago/Turabian StyleAllan A. Santos; Dayvson O. Guedes; Mário U.G. Barros; Samylla Oliveira; Ana B.F. Pacheco; Sandra M.F.O. Azevedo; Valéria F. Magalhães; Carlos J. Pestana; Christine Edwards; Linda A. Lawton; José Capelo-Neto. 2021. "Effect of hydrogen peroxide on natural phytoplankton and bacterioplankton in a drinking water reservoir: Mesocosm-scale study." Water Research 197, no. : 117069.
Primary consumers in freshwater ecosystems, such as the zooplankton organism Daphnia magna, are highly affected by cyanobacteria, both as they may use it as a food source but also by cyanobacterial metabolites present in the water. Here, we investigate the impacts of cyanobacterial metabolites focussing on the environmental realistic scenario of the naturally released mixture without crushing cyanobacterial cells or their uptake as food. Therefore, D. magna were exposed to two concentrations of cell free cyanobacterial spent medium from Microcystis aeruginosa PCC 7806 to represent higher and lower ecologically-relevant concentrations of cyanobacterial metabolites. Including microcystin-LR, 11 metabolites have been detected of which 5 were quantified. Hypothesising concentration and time dependent negative impact, survival, gene expression marking digestion and metabolism, oxidative stress response, cell cycle and molting as well as activities of detoxification and antioxidant enzymes were followed for 7 days. D. magna suffered from oxidative stress as both catalase and glutathione S-transferase enzyme activities significantly decreased, suggesting enzyme exhaustibility after 3 and 7 days. Moreover, gene-expressions of the 4 stress markers (glutathione S-transferase, glutathione peroxidase, catalase and thioredoxin) were merely downregulated after 7 days of exposure. Energy allocation (expression of glyceraldehyde-3-phosphate dehydrogenase) was increased after 3 days but decreased as well after 7 days exposure. Cell cycle was impacted time dependently but differently by the two concentrations, along with an increasing downregulation of myosin heavy chain responsible for cell arrangement and muscular movements. Deregulation of nuclear hormone receptor genes indicate that D. magna hormonal steering including molting seemed impaired despite no detection of microviridin J in the extracts. As a consequence of all those responses and presumably of more than investigated molecular and physiological changes, D. magna survival was impaired over time, in a concentration dependent manner. Our results confirm that besides microcystin-LR, other secondary metabolites contribute to negative impact on D. magna survival and stress response.
Gorenka Bojadzija Savic; Hervé Colinet; Myriam Bormans; Christine Edwards; Linda A. Lawton; Enora Briand; Claudia Wiegand. Cell free Microcystis aeruginosa spent medium affects Daphnia magna survival and stress response. Toxicon 2021, 195, 37 -47.
AMA StyleGorenka Bojadzija Savic, Hervé Colinet, Myriam Bormans, Christine Edwards, Linda A. Lawton, Enora Briand, Claudia Wiegand. Cell free Microcystis aeruginosa spent medium affects Daphnia magna survival and stress response. Toxicon. 2021; 195 ():37-47.
Chicago/Turabian StyleGorenka Bojadzija Savic; Hervé Colinet; Myriam Bormans; Christine Edwards; Linda A. Lawton; Enora Briand; Claudia Wiegand. 2021. "Cell free Microcystis aeruginosa spent medium affects Daphnia magna survival and stress response." Toxicon 195, no. : 37-47.
Although some studies have investigated the impact caused by chemicals used on water treatment (coagulants and oxidants) on cyanobacteria integrity, the isolated effect of shear stress during coagulation is still not fully understood. This study evaluated the impact of different velocity gradients, mixing times, and the addition of powdered activated carbon (PAC) on the integrity of Microcystis aeruginosa, Raphidiopsis raciborskii, and Dolichospermum circinale, known producers of toxin and taste and odor (T&O) compounds. No association was found between R. raciborskii cell lysis and velocity gradient, with or without PAC, demonstrating the high resilience of this taxon to shear stress. In contrast, an association was found for M. aeruginosa at the highest velocity gradient evaluated (1000 s−1) and for D. circinale above the lowest velocity gradient studied (600 s−1). After PAC addition, there was a reduction in the chances of finding M. aeruginosa intact cells above velocity gradient 800 s−1 at 45 s, while D. circinale show cell lysis in all the scenarios expect at 600 s−1 and 10 s of agitation. The additional impact of PAC on cell lysis may lead to more release of metabolites and shows the need to adjust the hydraulic conditions in the rapid mixing stage, especially when more “fragile” cyanobacteria are present. Neither cyanobacterial cell size nor morphology was shown to be relevant to shear stress sensitivity, indicating that cell wall composition might have been an important factor in controlling cell lysis.
Samylla Oliveira; Allan Clemente; Indira Menezes; Amanda Gois; Ismael Carloto; Linda Lawton; Jose Capelo-Neto. Hazardous cyanobacteria integrity response to velocity gradient and powdered activated carbon in water treatment plants. Science of The Total Environment 2021, 773, 145110 .
AMA StyleSamylla Oliveira, Allan Clemente, Indira Menezes, Amanda Gois, Ismael Carloto, Linda Lawton, Jose Capelo-Neto. Hazardous cyanobacteria integrity response to velocity gradient and powdered activated carbon in water treatment plants. Science of The Total Environment. 2021; 773 ():145110.
Chicago/Turabian StyleSamylla Oliveira; Allan Clemente; Indira Menezes; Amanda Gois; Ismael Carloto; Linda Lawton; Jose Capelo-Neto. 2021. "Hazardous cyanobacteria integrity response to velocity gradient and powdered activated carbon in water treatment plants." Science of The Total Environment 773, no. : 145110.
Cyanobacterial blooms are observed when high cell densities occur and are often dangerous to human and animal health due to the presence of cyanotoxins. Conventional drinking water treatment technology struggles to efficiently remove cyanobacterial cells and their metabolites during blooms, increasing costs and decreasing water quality. Although field applications of hydrogen peroxide have been shown to successfully suppress cyanobacterial growth, a rapid and accurate measure of the effect of oxidative stress on cyanobacterial cells is required. In the current study, H2O2 (5 and 20 mg L−1) was used to induce oxidative stress in Microcystis aeruginosa PCC 7813. Cell density, quantum yield of photosystem II, minimal fluorescence and microcystin (MC-LR, -LY, -LW, -LF) concentrations were compared when evaluating M. aeruginosa cellular stress. Chlorophyll content (determined by minimal fluorescence) decreased by 10% after 48 h while cell density was reduced by 97% after 24 h in samples treated with 20 mg L−1 H2O2. Photosystem II quantum yield (photosynthetic activity) indicated cyanobacteria cell stress within 6 h, which was considerably faster than the other methods. Intracellular microcystins (MC-LR, -LY, -LW and -LF) were reduced by at least 96% after 24 h of H2O2 treatment. No increase in extracellular microcystin concentration was detected, which suggests that the intracellular microcystins released into the surrounding water were completely removed by the hydrogen peroxide. Thus, photosynthetic activity was deemed the most suitable and rapid method for oxidative cell stress detection in cyanobacteria, however, an approach using combined methods is recomended for efficient water treatment management.
Indira Menezes; Declan Maxwell-McQueeney; José Capelo-Neto; Carlos J. Pestana; Christine Edwards; Linda A. Lawton. Oxidative stress in the cyanobacterium Microcystis aeruginosa PCC 7813: Comparison of different analytical cell stress detection assays. Chemosphere 2020, 269, 128766 .
AMA StyleIndira Menezes, Declan Maxwell-McQueeney, José Capelo-Neto, Carlos J. Pestana, Christine Edwards, Linda A. Lawton. Oxidative stress in the cyanobacterium Microcystis aeruginosa PCC 7813: Comparison of different analytical cell stress detection assays. Chemosphere. 2020; 269 ():128766.
Chicago/Turabian StyleIndira Menezes; Declan Maxwell-McQueeney; José Capelo-Neto; Carlos J. Pestana; Christine Edwards; Linda A. Lawton. 2020. "Oxidative stress in the cyanobacterium Microcystis aeruginosa PCC 7813: Comparison of different analytical cell stress detection assays." Chemosphere 269, no. : 128766.
Due to eutrophication, freshwater ecosystems frequently experience cyanobacterial blooms, many of which produce bioactive metabolites that can affect vertebrates and invertebrates life traits. Zooplankton are able to develop tolerance as a physiological response to cyanobacteria and their bioactive compounds, however, this comes with energetic cost that in turn influence Daphnia life traits and may impair populations. Vice versa, it has been suggested that Daphnia are able to reduce cyanobacterial dominance until a certain cyanobacterial density; it remains unclear whether Daphnia metabolites alone influence the physiological state and bioactive metabolites production of cyanobacteria. Hence, this study investigates mutual physiological reactions of toxic Microcystis aeruginosa PCC7806 and Daphnia magna. We hypothesize that a) the presence of D. magna will negatively affect growth, increase stress response and metabolites production in M. aeruginosa PCC7806 and b) the presence of M. aeruginosa PCC7806 will negatively affect physiological responses and life traits in D. magna. In order to test these hypotheses experiments were conducted in a specially designed co-culture chamber that allows exchange of the metabolites without direct contact. A clear mutual impact was evidenced. Cyanobacterial metabolites reduced survival of D. magna and decreased oxidative stress enzyme activity. Simultaneously, presence of D. magna did not affect photosynthetic activity. However, ROS increase and tendencies in cell density decrease were observed on the same day, suggesting possible energy allocation towards anti-oxidative stress enzymes, or other protection mechanisms against Daphnia infochemicals, as the strain managed to recover. Elevated concentration of intracellular and overall extracellular microcystin MC-LR, as well as intracellular concentrations of aerucyclamide A and D in the presence of Daphnia, indicating a potential protective or anti-grazing function. However, more research is needed to confirm these findings.
Gorenka Bojadzija Savic; Myriam Bormans; Christine Edwards; Linda Lawton; Enora Briand; Claudia Wiegand. Cross talk: Two way allelopathic interactions between toxic Microcystis and Daphnia. Harmful Algae 2020, 94, 101803 .
AMA StyleGorenka Bojadzija Savic, Myriam Bormans, Christine Edwards, Linda Lawton, Enora Briand, Claudia Wiegand. Cross talk: Two way allelopathic interactions between toxic Microcystis and Daphnia. Harmful Algae. 2020; 94 ():101803.
Chicago/Turabian StyleGorenka Bojadzija Savic; Myriam Bormans; Christine Edwards; Linda Lawton; Enora Briand; Claudia Wiegand. 2020. "Cross talk: Two way allelopathic interactions between toxic Microcystis and Daphnia." Harmful Algae 94, no. : 101803.
To tackle one of the Global Challenges of providing clean water, an ‘all in one’ photo reactor pod is designed carrying a supported benign photo-catalyst (TiO2) and an UV-LED light source which is utilised continuously to remove cyanotoxins in water.
H. Q. Nimal Gunaratne; Carlos J. Pestana; Nathan Skillen; Jianing Hui; S. Saravanan; Christine Edwards; John T. S. Irvine; Peter K. J. Robertson; Linda A. Lawton. ‘All in one’ photo-reactor pod containing TiO2 coated glass beads and LEDs for continuous photocatalytic destruction of cyanotoxins in water. Environmental Science: Water Research & Technology 2020, 6, 945 -950.
AMA StyleH. Q. Nimal Gunaratne, Carlos J. Pestana, Nathan Skillen, Jianing Hui, S. Saravanan, Christine Edwards, John T. S. Irvine, Peter K. J. Robertson, Linda A. Lawton. ‘All in one’ photo-reactor pod containing TiO2 coated glass beads and LEDs for continuous photocatalytic destruction of cyanotoxins in water. Environmental Science: Water Research & Technology. 2020; 6 (4):945-950.
Chicago/Turabian StyleH. Q. Nimal Gunaratne; Carlos J. Pestana; Nathan Skillen; Jianing Hui; S. Saravanan; Christine Edwards; John T. S. Irvine; Peter K. J. Robertson; Linda A. Lawton. 2020. "‘All in one’ photo-reactor pod containing TiO2 coated glass beads and LEDs for continuous photocatalytic destruction of cyanotoxins in water." Environmental Science: Water Research & Technology 6, no. 4: 945-950.
Blooms of the cyanobacterium Nodularia spumigena occur regularly in the Baltic Sea typically producing a wide range of bioactive peptides including the hepatotoxin nodularin (NOD), spumigins, anabaenopeptins and nodulopeptins (molecular weights: 917, 901 and 899 Da). This study reports the production of intracellular and extracellular NOD and nodulopeptin 901 (the major secondary metabolites), at various nitrate and phosphorus concentrations produced by N. spumigena KAC 66 which had been originally isolated from the Baltic Sea. The growth was observed by cell biomass and intracellular and extracellular peptides monitored by high-performance liquid chromatography with photodiode array and mass spectrometry (HPLC-PDA-MS). In the present work, it was found that high concentrations of nitrate and phosphorus have a considerable effect on biomass and toxin levels of N. spumigena. In common with many studies, the maximum amount of NOD was retained within the cells during 5 weeks of growth. In contrast, as much as ~ 40% of nodulopeptin 901 was excreted into the medium throughout the duration of experiments. At 6.5 and 3.5 mg L−1 nitrate, the maximum concentrations of peptide per unit biomass was 1.78 ng NOD (in week 4) and 1.42 ng nodulopeptin 901 μg−1 (in week 3) were detected. However, the high concentrations of both peptides were produced in the absence of nitrate. The phosphate experiment indicated growth, and peptide production was dependent on availability of phosphorus. At 0 mg L−1 of phosphate, an increased amount of intracellular (502.4 ng μg−1 biomass) nodulopeptin 901 was recorded. This report evaluates the effect of nutrients on the production of biomass and toxins, which may predict the formation and control of blooms of N. spumigena in the Baltic Sea. It also provides information to improve the growth conditions to produce high biomass and toxins under suitable conditions, which may be helpful in the research. The results from the current study will also be helpful to predict about possible blooms of N. spumigena in the Baltic Sea with reference to increase or decrease in nitrate and phosphate concentrations.
Shaista Hameed; Linda A. Lawton; Christine Edwards. Phosphate and nitrate supplementations to evaluate the effect on cell biomass, intra and extracellular nodularin and nodulopeptin 901 produced by the cyanobacterium Nodularia spumigena KAC 66. Environmental Biology of Fishes 2019, 32, 937 -950.
AMA StyleShaista Hameed, Linda A. Lawton, Christine Edwards. Phosphate and nitrate supplementations to evaluate the effect on cell biomass, intra and extracellular nodularin and nodulopeptin 901 produced by the cyanobacterium Nodularia spumigena KAC 66. Environmental Biology of Fishes. 2019; 32 (2):937-950.
Chicago/Turabian StyleShaista Hameed; Linda A. Lawton; Christine Edwards. 2019. "Phosphate and nitrate supplementations to evaluate the effect on cell biomass, intra and extracellular nodularin and nodulopeptin 901 produced by the cyanobacterium Nodularia spumigena KAC 66." Environmental Biology of Fishes 32, no. 2: 937-950.
While the intracellular function of many toxic and bioactive cyanobacterial metabolites is not yet known, microcystins have been suggested to have a protective role in the cyanobacterial metabolism, giving advantage to toxic over nontoxic strains under stress conditions. The zooplankton grazer Daphnia reduce cyanobacterial dominance until a certain density, which may be supported by Daphnia exudates, affecting the cyanobacterial physiological state and metabolites' production. Therefore, we hypothesized that D. magna spent medium will impact the production of cyanobacterial bioactive metabolites and affect cyanobacterial photosynthetic activity in the nontoxic, but not the toxic strain. Microcystin (MC-LR and des-MC-LR) producing M. aeruginosa PCC7806 and its non-microcystin producing mutant were exposed to spent media of different D. magna densities and culture durations. D. magna spent medium of the highest density (200/L) cultivated for the shortest time (24 h) provoked the strongest effect. D.magna spent medium negatively impacted the photosynthetic activity of M. aeruginosa PCC7806, as well as the dynamics of intracellular and extracellular cyanobacterial metabolites, while its mutant was unaffected. In the presence of Daphnia medium, microcystin does not appear to have a protective role for the strain. On the contrary, extracellular cyanopeptolin A increased in M. aeruginosa PCC7806 although the potential anti-grazing role of this compound would require further studies.
Gorenka Bojadzija Savic; Christine Edwards; Enora Briand; Linda Lawton; Claudia Wiegand; Myriam Bormans. Daphnia magna Exudates Impact Physiological and Metabolic Changes in Microcystis aeruginosa. Toxins 2019, 11, 421 .
AMA StyleGorenka Bojadzija Savic, Christine Edwards, Enora Briand, Linda Lawton, Claudia Wiegand, Myriam Bormans. Daphnia magna Exudates Impact Physiological and Metabolic Changes in Microcystis aeruginosa. Toxins. 2019; 11 (7):421.
Chicago/Turabian StyleGorenka Bojadzija Savic; Christine Edwards; Enora Briand; Linda Lawton; Claudia Wiegand; Myriam Bormans. 2019. "Daphnia magna Exudates Impact Physiological and Metabolic Changes in Microcystis aeruginosa." Toxins 11, no. 7: 421.
For the first time, a cellulose polymorph is used as a starting material for improved photocatalytic hydrogen production.
Colby Chang; Nathan Skillen; Sanjay Nagarajan; Kathryn Ralphs; John T. S. Irvine; Linda Lawton; Peter K. J. Robertson. Using cellulose polymorphs for enhanced hydrogen production from photocatalytic reforming. Sustainable Energy & Fuels 2019, 3, 1971 -1975.
AMA StyleColby Chang, Nathan Skillen, Sanjay Nagarajan, Kathryn Ralphs, John T. S. Irvine, Linda Lawton, Peter K. J. Robertson. Using cellulose polymorphs for enhanced hydrogen production from photocatalytic reforming. Sustainable Energy & Fuels. 2019; 3 (8):1971-1975.
Chicago/Turabian StyleColby Chang; Nathan Skillen; Sanjay Nagarajan; Kathryn Ralphs; John T. S. Irvine; Linda Lawton; Peter K. J. Robertson. 2019. "Using cellulose polymorphs for enhanced hydrogen production from photocatalytic reforming." Sustainable Energy & Fuels 3, no. 8: 1971-1975.
This study investigated the coupling of sulfate radical generating oxidants, (persulfate, PS and peroxymonosulfate, PMS) with TiO2 photocatalysis for the degradation of microcystin-LR (MC-LR). Treatment efficiency was evaluated by estimating the electrical energy per order (EEO). Oxidant addition at 10 mg/L reduced the energy requirements of the treatment by 60% and 12% for PMS and PS, respectively compared with conventional photocatalysis. Quenching studies indicated that both sulfate and hydroxyl radicals contributed towards the degradation of MC-LR for both oxidants, while Electron Paramagnetic Resonance (EPR) studies confirmed that the oxidants prolonged that lifetime of both radicals (concentration maxima shifted from 10 to 20 min), allowing for bulk diffusion and enhancing cyanotoxin removal. Structural identification of transformation products (TPs) formed during all treatments, indicated that early stage degradation of MC-LR occurred mainly on the aromatic ring and conjugated carbon double bonds of the ADDA amino acid. In addition, simultaneous hydroxyl substitution of the aromatic ring and the conjugated double carbon bonds of ADDA (m/z = 1027.5) are reported for the first time. Oxidant addition also increased the rates of formation/degradation of TPs and affected the overall toxicity of the treated samples. The detoxification and degradation order of the treatments was UVA/TiO2/PMS > UVA/TiO2/PS>> UVA/TiO2.
M.G. Antoniou; I. Boraei; M. Solakidou; Y. Deligiannakis; M. Abhishek; L.A. Lawton; C. Edwards. Enhancing photocatalytic degradation of the cyanotoxin microcystin-LR with the addition of sulfate-radical generating oxidants. Journal of Hazardous Materials 2018, 360, 461 -470.
AMA StyleM.G. Antoniou, I. Boraei, M. Solakidou, Y. Deligiannakis, M. Abhishek, L.A. Lawton, C. Edwards. Enhancing photocatalytic degradation of the cyanotoxin microcystin-LR with the addition of sulfate-radical generating oxidants. Journal of Hazardous Materials. 2018; 360 ():461-470.
Chicago/Turabian StyleM.G. Antoniou; I. Boraei; M. Solakidou; Y. Deligiannakis; M. Abhishek; L.A. Lawton; C. Edwards. 2018. "Enhancing photocatalytic degradation of the cyanotoxin microcystin-LR with the addition of sulfate-radical generating oxidants." Journal of Hazardous Materials 360, no. : 461-470.
There has been a steady rise in the incidences of algal blooms globally, and worryingly, there is increasing evidence that changes in the global climate are leading to a shift toward cyanobacterial blooms. Many cyanobacterial genera are harmful, producing several potent toxins, including microcystins, for which there are over 90 described analogues. There are a wide range of negative effects associated with these toxins including gastroenteritis, cytotoxicity, hepatotoxicity and neurotoxicity. Although a variety of oxidation based treatment methods have been described, ozonation and advanced oxidation are acknowledged as most effective as they readily oxidise microcystins to non-toxic degradation products. However, most ozonation technologies have challenges for scale up including high costs and sub-optimum efficiencies, hence, a low cost and scalable ozonation technology is needed. Here we designed a low temperature plasma dielectric barrier discharge (DBD) reactor with an incorporated fluidic oscillator for microbubble delivery of ozone. Both technologies have the potential to drastically reduce the costs of ozonation at scale. Mass spectrometry analysis revealed very rapid (<2 min) destruction of two pure microcystins (MC-LR and MC-RR), together with removal of by-products even at low flow rate 1 L min−1 where bubble size was 0.56–0.6 mm and the ozone concentration within the liquid was 20 ppm. Toxicity levels were calculated through protein phosphatase inhibition assays and indicated loss of toxicity as well as confirming the by-products were also non-toxic. Finally, treatment of whole Microcystis aeruginosa cells showed that even at these very low ozone levels, cells can be killed and toxins (MC-LR and Desmethyl MC-LR) removed. Little change was observed in the first 20 min of treatment followed by rapid increase in extracellular toxins, indicating cell lysis, with most significant release at the higher 3 L min−1 flow rate compared to 1 L min−1. This lab-scale investigation demonstrates the potential of the novel plasma micro reactor with applications for in situ treatment of harmful algal blooms and cyanotoxins.
Jagroop Pandhal; Anggun Siswanto; Dmitriy Kuvshinov; William Zimmerman; Linda Lawton; Christine Edwards. Cell Lysis and Detoxification of Cyanotoxins Using a Novel Combination of Microbubble Generation and Plasma Microreactor Technology for Ozonation. Frontiers in Microbiology 2018, 9, 678 .
AMA StyleJagroop Pandhal, Anggun Siswanto, Dmitriy Kuvshinov, William Zimmerman, Linda Lawton, Christine Edwards. Cell Lysis and Detoxification of Cyanotoxins Using a Novel Combination of Microbubble Generation and Plasma Microreactor Technology for Ozonation. Frontiers in Microbiology. 2018; 9 ():678.
Chicago/Turabian StyleJagroop Pandhal; Anggun Siswanto; Dmitriy Kuvshinov; William Zimmerman; Linda Lawton; Christine Edwards. 2018. "Cell Lysis and Detoxification of Cyanotoxins Using a Novel Combination of Microbubble Generation and Plasma Microreactor Technology for Ozonation." Frontiers in Microbiology 9, no. : 678.
A simple, rapid UHPLC-MS/MS method has been developed and optimised for the quantitation of microcystins and nodularin in wide variety of sample matrices. Microcystin analogues targeted were MC-LR, MC-RR, MC-LA, MC-LY, MC-LF, LC-LW, MC-YR, MC-WR, [Asp3] MC-LR, [Dha7] MC-LR, MC-HilR and MC-HtyR. Optimisation studies were conducted to develop a simple, quick and efficient extraction protocol without the need for complex pre-analysis concentration procedures, together with a rapid sub 5 min chromatographic separation of toxins in shellfish and algal supplement tablet powders, as well as water and cyanobacterial bloom samples. Validation studies were undertaken on each matrix-analyte combination to the full method performance characteristics following international guidelines. The method was found to be specific and linear over the full calibration range. Method sensitivity in terms of limits of detection, quantitation and reporting were found to be significantly improved in comparison to LC-UV methods and applicable to the analysis of each of the four matrices. Overall, acceptable recoveries were determined for each of the matrices studied, with associated precision and within-laboratory reproducibility well within expected guidance limits. Results from the formalised ruggedness analysis of all available cyanotoxins, showed that the method was robust for all parameters investigated. The results presented here show that the optimised LC-MS/MS method for cyanotoxins is fit for the purpose of detection and quantitation of a range of microcystins and nodularin in shellfish, algal supplement tablet powder, water and cyanobacteria. The method provides a valuable early warning tool for the rapid, routine extraction and analysis of natural waters, cyanobacterial blooms, algal powders, food supplements and shellfish tissues, enabling monitoring labs to supplement traditional microscopy techniques and report toxicity results within a short timeframe of sample receipt. The new method, now accredited to ISO17025 standard, is simple, quick, applicable to multiple matrices and is highly suitable for use as a routine, high-throughout, fast turnaround regulatory monitoring tool.
Andrew D. Turner; Julia Waack; Adam Lewis; Christine Edwards; Linda Lawton. Development and single-laboratory validation of a UHPLC-MS/MS method for quantitation of microcystins and nodularin in natural water, cyanobacteria, shellfish and algal supplement tablet powders. Journal of Chromatography B 2018, 1074-1075, 111 -123.
AMA StyleAndrew D. Turner, Julia Waack, Adam Lewis, Christine Edwards, Linda Lawton. Development and single-laboratory validation of a UHPLC-MS/MS method for quantitation of microcystins and nodularin in natural water, cyanobacteria, shellfish and algal supplement tablet powders. Journal of Chromatography B. 2018; 1074-1075 ():111-123.
Chicago/Turabian StyleAndrew D. Turner; Julia Waack; Adam Lewis; Christine Edwards; Linda Lawton. 2018. "Development and single-laboratory validation of a UHPLC-MS/MS method for quantitation of microcystins and nodularin in natural water, cyanobacteria, shellfish and algal supplement tablet powders." Journal of Chromatography B 1074-1075, no. : 111-123.
Alternative renewable energy must emerge to sustainably meet the energy demands of the present and future. Current alternatives to fossil fuels are electricity from solar, wind and tidal energies and biofuels. Biofuels, especially bioethanol could be produced from lignocellulosic feedstock via pre-treatment and fermentation. The cellulose I content of most lignocellulosic feedstock is significant, yet its highly crystalline amphiphilic structure interlinked with the lignin network makes it difficult to process for bioethanol production. Processing lignocellulosic biomass via a range of physico-chemical, mechanical and biological pre-treatment methods have been well established, however a relatively new area on the use of cellulose II (a polymorph of native cellulose obtained via mercerisation or regeneration) for the production of bioethanol is still in its early stages. Hence, this review discusses in detail the advantages of using cellulose II over cellulose I as feedstock for bioethanol production. Furthermore, current green and sustainable methods for cellulose II production and the advantages and disadvantages of each method are discussed. In addition, examples from literature reporting higher fermentable sugar and bioethanol yields using cellulose II as feedstock are reviewed, thereby highlighting its importance in the field of bioethanol production. The conclusion from this review suggests that, in all the cases studied, fermentable sugar and/or bioethanol production was found to be higher when cellulose II was used as feedstock instead of native cellulose/lignocellulosic biomass. This higher yield could be attributed to the modified structural and lattice arrangement of cellulose II, its porous volume and degree of polymerisation.Engineering and Physical Sciences Research Council (Project no. EP/K036769/1) ; Queen's University Belfast's Ph.D. studentship
Sanjay Nagarajan; Nathan C. Skillen; John Irvine; Linda Lawton; Peter Robertson. Cellulose II as bioethanol feedstock and its advantages over native cellulose. Renewable and Sustainable Energy Reviews 2017, 77, 182 -192.
AMA StyleSanjay Nagarajan, Nathan C. Skillen, John Irvine, Linda Lawton, Peter Robertson. Cellulose II as bioethanol feedstock and its advantages over native cellulose. Renewable and Sustainable Energy Reviews. 2017; 77 ():182-192.
Chicago/Turabian StyleSanjay Nagarajan; Nathan C. Skillen; John Irvine; Linda Lawton; Peter Robertson. 2017. "Cellulose II as bioethanol feedstock and its advantages over native cellulose." Renewable and Sustainable Energy Reviews 77, no. : 182-192.
Oluwatosin Tokode; Radhakrishna Prabhu; Linda A. Lawton; Peter Robertson. A photocatalytic impeller reactor for gas phase heterogeneous photocatalysis. Journal of Environmental Chemical Engineering 2017, 5, 3942 -3948.
AMA StyleOluwatosin Tokode, Radhakrishna Prabhu, Linda A. Lawton, Peter Robertson. A photocatalytic impeller reactor for gas phase heterogeneous photocatalysis. Journal of Environmental Chemical Engineering. 2017; 5 (4):3942-3948.
Chicago/Turabian StyleOluwatosin Tokode; Radhakrishna Prabhu; Linda A. Lawton; Peter Robertson. 2017. "A photocatalytic impeller reactor for gas phase heterogeneous photocatalysis." Journal of Environmental Chemical Engineering 5, no. 4: 3942-3948.
Photocatalytic technology using TiO2 is one of the emerging approaches for water treatment, especially as a final step to remove complex organics such as pesticides, hormones or humic acids. Titanium dioxide (TiO2) is a semiconductor material with strong UV absorption band and exhibits strong photocatalytic activity. The photocatalytic activity of TiO2 powders have been extensively studied, using UV light sources. However, the incident photons that initiate the process of photocatalytic oxidation using titanium dioxide are not efficiently used, this is responsible for the low photonic efficiency that characterise oxidation of aqueous pollutants hence its limitation in industrial applications. Periodic illumination has been investigated as a means of increasing the photonic efficiency in a photoreactor with acid orange as a model pollutant. Results indicate more than four-fold increase in photonic efficiency through periodic illumination compared to continuous illumination. This approach can improve the energy efficiency of the photocatalytic water treatment systems.
R. Prabhu; F. Hewitt; G. Georgieva; L. A. Lawton; H. N. Meenakshi; P. K. J. Robertson. Energy efficient operation of photocatalytic reactors based on UV LEDs for pollution remediation in water. OCEANS 2017 - Aberdeen 2017, 1 -5.
AMA StyleR. Prabhu, F. Hewitt, G. Georgieva, L. A. Lawton, H. N. Meenakshi, P. K. J. Robertson. Energy efficient operation of photocatalytic reactors based on UV LEDs for pollution remediation in water. OCEANS 2017 - Aberdeen. 2017; ():1-5.
Chicago/Turabian StyleR. Prabhu; F. Hewitt; G. Georgieva; L. A. Lawton; H. N. Meenakshi; P. K. J. Robertson. 2017. "Energy efficient operation of photocatalytic reactors based on UV LEDs for pollution remediation in water." OCEANS 2017 - Aberdeen , no. : 1-5.
Gloria Naa Dzama Addico; Linda Lawton; Christine Edwards. Hepatotoxic-Microcystins in Two Drinking Water Reservoirs in the Central Region of Ghana. Toxicology and Forensic Medicine – Open Journal 2017, 2, 1 -11.
AMA StyleGloria Naa Dzama Addico, Linda Lawton, Christine Edwards. Hepatotoxic-Microcystins in Two Drinking Water Reservoirs in the Central Region of Ghana. Toxicology and Forensic Medicine – Open Journal. 2017; 2 (1):1-11.
Chicago/Turabian StyleGloria Naa Dzama Addico; Linda Lawton; Christine Edwards. 2017. "Hepatotoxic-Microcystins in Two Drinking Water Reservoirs in the Central Region of Ghana." Toxicology and Forensic Medicine – Open Journal 2, no. 1: 1-11.
Sanjay Nagarajan; Lorenzo Stella; Linda Lawton; John Irvine; Peter Robertson. Mixing regime simulation and cellulose particle tracing in a stacked frame photocatalytic reactor. Chemical Engineering Journal 2017, 313, 301 -308.
AMA StyleSanjay Nagarajan, Lorenzo Stella, Linda Lawton, John Irvine, Peter Robertson. Mixing regime simulation and cellulose particle tracing in a stacked frame photocatalytic reactor. Chemical Engineering Journal. 2017; 313 ():301-308.
Chicago/Turabian StyleSanjay Nagarajan; Lorenzo Stella; Linda Lawton; John Irvine; Peter Robertson. 2017. "Mixing regime simulation and cellulose particle tracing in a stacked frame photocatalytic reactor." Chemical Engineering Journal 313, no. : 301-308.