Microbial water quality in pangasius and tilapia aquaculture systems in five regions of Bangladesh

Aims@#To determine abundance of potential pathogenic microorganisms in pangasius and tilapia farms in five major fish-producing areas in Bangladesh by PCR approaches.@*Methodology and results@#Important microbial water quality indicators were studied in water of 38 fish farms producing pangasius (Pangasianodon hypophthalmus) and tilapia (Oreochromis niloticus) in five major fish-producing areas of Bangladesh. The parameters included physicochemical data and PCR detection of total coliforms and E. coli, species of potentially pathogenic Vibrio, and cyanobacterial genes encoding the toxins microcystin and saxitoxin. Quantitative PCR showed that coliform bacteria occurred in all fish farms with densities from one to 2.2 × 105 per mL, while E. coli ranged from none to 5.0 × 104 per mL. Numbers of total coliforms and E. coli were higher in pangasius farms than in tilapia farms, and when high abundances occurred, coliform bacteria and E. coli bacteria co-varied. Detection of Vibrio-specific genes indicated presence of Vibrio species in 76% of the farms and included V. vulnificus and V. cholerae. The human pathogen type of V. cholerae (carrying the ctxA gene) and the fish pathogen V. parahaemolyticus were not detected. The microcystin-encoding mcyE gene ranged from undetectable to 2.6 × 105 copies per mL and tended to be highest in pangasius farms. The saxitoxin-encoding gene sxtA was not found in any of the farms. @*Conclusion, significance and impact of study@#Based on the high abundance of especially coliform bacteria and E. coli, we recommend more efficient water quality monitoring systems to improve detection and control of fecal coliforms and to reduce presence of microcystin-producing cyanobacteria in aquaculture farms in Bangladesh

Caracterização e avaliação de fatores que determinam a remoção de microcistina-LR em carvão ativado granular produzido a partir de diferentes matérias-primas / Characterization and evaluation of factors influencing microcystin-LR removal by granular activated carbon produced from different raw materials

RESUMO As microcistinas (MC), que estão entre as cianotoxinas mais encontradas em florações de cianobactérias, não são eficientemente removidas pelas tecnologias do ciclo completo de tratamento de água. Como barreira adicional para sua remoção, destaca-se o processo de adsorção com carvão ativado granular (CAG). Esta pesquisa comparou a eficiência de remoção de MC-LR por sete CAG produzidos a partir de diferentes matérias-primas, analisando as propriedades das amostras: umidade, teor de cinzas, pH e características texturais. Inicialmente, os resultados indicaram que as propriedades dos CAG foram influenciadas pelo material de origem, assim como pelo método de produção. Nos ensaios de adsorção, o modelo de Langmuir indicou que, em quatro horas, com dosagem de 100 mg.L-1, o CAG de linhito (CGLIN) apresentou a maior capacidade de remoção (97,2%) de MC-LR (Co: 115,1 µg.L-1), com qe,máx de 10,6 mg.g-1. O volume de mesoporos influenciou significativamente a capacidade adsortiva de MC dos carvões avaliados (r=0,98, Pearson). Esses resultados podem oferecer subsídios para a aplicação do processo de adsorção de MC-LR em estações de tratamento de água (ETA) para a minimização de intoxicações por água contaminada.

ABSTRACT Microcystins (MC), which are among the cyanotoxins more commonly found in cyanobacterial blooms, are not efficiently removed by full-cycle water treatment technologies. As an additional barrier, there is the adsorption process with granular activated carbon (GAC). This research compared the efficiency of MC-LR removal by seven GACs produced from different raw materials, analyzing these samples' properties: moisture, ash content, pH and textural characteristics. Initially, the results indicated that the GAC properties were influenced by the source material, as well as by the production method. In the adsorption assays, the Langmuir model indicated that in 4h, with 100 mg.L-1 dosage, the granular activated carbon of lignite (CGLIN) had the highest MC-LR (Co: 115.1 µg.L-1) removal capacity (97.2%), with qe,max of 10.6 mg.g-1. The volume of mesopores significantly influenced the adsorption capacity of microcystin by the evaluated GACs (r=0.98, Pearson). These results can support the application of the MC-LR adsorption process in water treatment plants to minimize intoxication with contaminated water.

The transformation of microcystin-LR during tap water treatment process and analysis of its degradation products / 中华预防医学杂志

Objective@#To establish a liquid chromatography-tandem mass spectrometry (LC/MS/MS) method for the determination of microcystin-LR (MC-LR) in drinking water, investigate its removal efficiency during tap water advanced treatment process and analyze its degradation products in the tap water.@*Methods@#Two parallel water samples were collected from each point of tap water advanced treatment process in September 2015, November 2015 and January 2016, respectively, and treated by mixing, filtration, concentration, elution, nitrogen blow and re-dissolvement. The samples were analyzed by LC/MS/MS to determine the MC-LR concentration and its removal efficiency during treatment process. The combination of actual water enrichment (including source water enrichment of 50 times and 1 500 times concentrated, finished water enrichment of 50 times and 2 500 times concentrated) and laboratory simulated water (including the mixture of MC-LR and liquid chlorine in the mass ratio of 1∶10, 1∶20, 1∶100 and 1∶1 000, respectively) were used to qualitative analyze the MC-LR degradation products by Orbitrap mass spectrometry.@*Results@#The linearity of MC-LR ranged from 2 to 200 μg/L with the detection limit of 0.007 9 μg/L and the limit of quantification of 0.026 3 μg/L. The recovery rate of MC-LR from different contration in drinking water were from 94.88%-101.47%. The intra-day precision was 2.51%-7.93% and the intra-day precision was 3.24%-8.41%. The average concentration of MC-LR in source water was (0.631±0.262) μg/L, 94.0% of which can be removed by ozone exposure while the concentrate was (0.038±0.016) μg/L, biological pre-treatment and chlorination. The remaining can hardly be removed by sand filtration, ozone exposure, activated carbon, ultrafiltration and other processes. The MC-LR average concentration in the finished water maintained at about (0.036±0.016) μg/L. Degradation products including hydroxy-microcystin, methyl-hydroxy-microcystin, methyl-microcystin were identified in the laboratory simulated water of the mixture of MC-LR and liquid chlorine in the mass ratio of 1∶10.@*Conclusion@#The established MC-LR detection method can be well applied to the monitoring of MC-LR in drinking water due to its simple pre-treatment process and good methodological validation parameters. The degradation products of treatment processes was different.

Electrochemical Immunosensor for Microcystin-LR Detection Based on Nano-composite Material Immobilization and Enzymatic Amplification / 分析化学

A competitive electrochemical immunosensor based on the nano-composite material immobilization and enzymatic amplification was designed for detection of microcystin-LR. Gold nanoparticles/carboxylated multi-walled carbon nanotubes (AuNPs/c-MWCNTs) composite film, which formed by electrodepositing of AuNPs on the C-MWCNTs modified glassy carbon electrode,was used for the immobilization of the antibody of microcystin-LR (anti-MCLR). Horseradish peroxidase (HRP) was introduced onto the nanocomposite interface by HRP blocked sensing interface and specific capture of antibody with target. It could be employed to catalyze the reduction of H2O2, and to block the possible remaining active sites as well. A competitive immunoreaction between antigen and MCLR-HRP was used for target analysis. In the presence of H2O2and hydroquinone (HQ),MCLR could be indirectly detected with differential pulse voltammetry (DPV) method by determining the reduction current of HQ. Under the optimal conditions, the proposed immunosensor exhibited wide linear ranges in the concentration ranges of 0.1-100.0 μg/L, with a detection limit of 0.038 μg/L (S/N = 3,n=8). The immunosensor showed good specificity, stability and sensitivity. It was used to determine MCLR in real water samples with the recoveries of 72.9%-117.3%.

Hierarquização da eficiência de remoção de cianotoxinas por meio de adsorção em carvão ativado granular / Evaluation of hierarchy of cyanotoxin removal by adsorption onto granular activated carbon

RESUMO O trabalho objetivou avaliar a remoção concomitante de duas cianotoxinas - microcistina-LR e saxitoxina-STX - por meio da adsorção em carvão ativado granular. Em primeira etapa, três carvões de granulometrias distintas, dois de coco de dendê e um mineral, foram avaliados na adsorção de microcistina-LR em água destilada e tratada com concentrações de 3,9 a 9,4 ug.L-1. O carvão de coco de dendê de menor granulometria apresentou desempenho mais uniforme, tanto no que tange à remoção (%) de microcistina-LR, quanto ao volume de efluente produzido consoante com as recomendações do padrão de potabilidade brasileiro. Em segunda etapa, apenas para o carvão selecionado na etapa precedente, concentrações de microcistina-LR e saxitoxina-STX aproximadamente 50% superiores dos limites do mesmo padrão de potabilidade foram dispersas em água destilada. Tais ensaios de adsorção evidenciaram que apenas a adsorção de saxitonina não foi influenciada pela simultaneidade das duas cianotoxinas.

ABSTRACT This study focused on the simultaneous removal of two cyanotoxins - microcystin-LR and saxitoxin-STX - by means of adsorption onto granular activated carbon. In first step, three carbons with different granulometry (dende coconut and mineral) were evaluated on adsorption of microcystin-LR in distilled and treated waters in concentrations at about 3.9 to 9.4 ug.L-1. The dende coconut carbon with lower granulometry showed higher performance according to the limits established by Brazilian Drinking Water Standards. In second step, with the selected carbon in previous step, concentrations of the two cyanotoxins 50% higher than those limits were dispersed in distilled water. The tests pointed out that only saxitoxin-STX removal was not affect by the presence both cyanotoxins.

Can microcystins affect zooplankton structure community in tropical eutrophic reservoirs? / Microcistinas podem afetar a estrutura da comunidade zooplanctônica em reservatórios eutróficos tropicais?

Abstract The aim of our study was to assess whether cyanotoxins (microcystins) can affect the composition of the zooplankton community, leading to domination of microzooplankton forms (protozoans and rotifers). Temporal variations in concentrations of microcystins and zooplankton biomass were analyzed in three eutrophic reservoirs in the semi-arid northeast region of Brazil. The concentration of microcystins in water proved to be correlated with the cyanobacterial biovolume, indicating the contributions from colonial forms such as Microcystis in the production of cyanotoxins. At the community level, the total biomass of zooplankton was not correlated with the concentration of microcystin (r2 = 0.00; P > 0.001), but in a population-level analysis, the biomass of rotifers and cladocerans showed a weak positive correlation. Cyclopoid copepods, which are considered to be relatively inefficient in ingesting cyanobacteria, were negatively correlated (r2 = – 0.01; P > 0.01) with the concentration of cyanotoxins. Surprisingly, the biomass of calanoid copepods was positively correlated with the microcystin concentration (r2 = 0.44; P > 0.001). The results indicate that allelopathic control mechanisms (negative effects of microcystin on zooplankton biomass) do not seem to substantially affect the composition of mesozooplankton, which showed a constant and high biomass compared to the microzooplankton (rotifers). These results may be important to better understand the trophic interactions between zooplankton and cyanobacteria and the potential effects of allelopathic compounds on zooplankton.

Resumo Com o objetivo de avaliar se as cianotoxinas (microcistinas) podem afetar a composição da comunidade zooplanctônica, levando à dominância de formas microzooplanctônicas (protozoários e rotiferos), as variações nas concentrações de microcistina e a biomassa do zooplâncton foram analisadas em três reservatórios eutróficos na região semi-árida do nordeste brasileiro. A concentração de microcistinas na água esteve correlacionada com o biovolume de cianobactérias, indicando a contribuição de formas coloniais como Microcystis na produção de cianotoxinas. A nível de comunidade, a biomassa total do zooplâncton não apresentou correlacão com a concentração de microcistina (r2 = 0.00; P > 0.001), mas em uma análise a nível de populações, a biomassa de rotíferos e cladóceros apresentou uma fraca correlação positiva. Copépodos Cyclopoida, os quais são considerados relativamente ineficientes na ingestão de cianobactérias, estiveram negativamente correlacionados com a concentração de microcistinas (r2 = - 0.01; P > 0.01). Surpreendentemente, a biomassa de copépodos Calanoida foi positivamente correlacionada com a concentração de cianotoxinas (r2 = 0.44; P > 0.001). Os resultados indicam que mecanismos de controle alelopáticos (efeitos negativos da microcistina sobre o zooplâncton) parecem não afetar substancialmente a composição do mesozooplâncton, que apresentou uma alta e constante biomassa, quando comparada à biomassa do microzooplâncton (rotíferos). Esses resultados podem ser importantes para um melhor entendimento das interações tróficas entre o zooplâncton e cianobactérias, e do efeito potencial de compostos alelopáticos sobre o zooplâncton.

Effect of glutathione on liver antioxidative function of microcystin-LR-induced mice / 重庆医学

Objective To study the effect of glutathione(GSH)on liver antioxidative function of microcystin‐LR(MC‐LR)‐in‐duced mice .Methods Forty healthy clean class KM 5‐week old mice were selected and divided into five groups by the random sam‐pling method ,including the norml saline control group ,GSH control group ,MC‐LR group ,MC‐LR+low dose GSH group and MC‐LR+high dose GSH group ,8 cases in each group ,half male and half female .The experiment lasted for 15 d by intraperitoneal injec‐tion of MC‐LR ,then the liver histopathological changes ,liver tissue activity of superoxide dismutase (SOD) ,glutathione peroxidase (GSH‐Px)and content of malondialdehyde(MDA) were detected .Results Compared with the normal saline control group ,liver cell GSH level ,SOD and GSH‐Px activities in the MC‐LR group were significantly decreased (P<0 .05) ,while the MDA level was sig‐nificantly increased (P<0 .05) .Compared with the MC‐LR group ,the GSH level ,SOD and GSH‐Px activities in the MC‐LR+low dose GSH group and MC‐LR+high dose GSH group were significantly increased (P<0 .05) ,while the MDA level was significant‐ly decreased(PP<0 .05) .Conclusion The GSH intervention can alleviate MC‐LR induced mouse liver oxidative toxicity and has protective effect on the liver to some extent .

The protective effects of glutathione on renal oxidative damage induced by microcystin-LR on mice / 重庆医学

Objective To study the protection of glutathione (GSH) on renal oxidative damage to mice which caused by mi‐crocystin‐LR(MC‐LR) .Methods Forty healthy KM mice were divided into five groups by randomly sampling ,which were saline control group ,GSH control group ,MC‐LR group ,low dose GSH +MC‐LR group and high dose GSH +MC‐LR group ,and the ex‐periment was lasting 15 days by intraperitoneal injection .Then we took out the kidney for pathological observation and detected the activity of CAT ,SOD ,GSH‐Px and the content of GSH ,MDA .Results Compared with control group ,the MC‐LR increased the content of MDA[(2 .31 ± 0 .22)nmol/mg prot ,P=0 .000] and decreased the content of GSH[(0 .68 ± 0 .02)mg/g prot] .The activi‐ty of CAT[(320 .54 ± 38 .99)nmol/mg prot] ,SOD[(180 .93 ± 15 .30)U/mg prot] ,GSH‐Px[(295 .11 ± 42 .40)U/mg prot](P<0 .05) .However ,after GSH was given ,compared with MC‐LR group ,MDA content[(1 .94 ± 0 .12)nmol/mg prot]of high dose GSH+MC‐LR group significantly decreased (P<0 .05) ,GSH content[(1 .01 ± 0 .08)mg/g prot ,(1 .08 ± 0 .16)mg/g prot]and CAT activity[(383 .46 ± 21 .98)nmol/mg prot ,(428 .50 ± 28 .61)nmol/mg prot] of both GSH groups significantly increased (P<0 .05) ,the activity of SOD[(222 .01 ± 11 .51)U/mg prot] and GSH‐Px[(358 .37 ± 20 .29)U/mg prot] of high dose GSH +MC‐LR group significantly increased (P<0 .05) .Conclusion MC‐LR may cause renal oxidative damage through promoting the lipid perox‐idation on renal cells .The GSH may reach a certain protective effect on kidney by reducing the lipid peroxidation ,improving the an‐tioxidant activity ,and removing oxygen free radicals .

Remoção de microcistina-LR de águas eutrofizadas por clarificação e filtração seguidas de adsorção em carvão ativado granular / Removal of microcystin-LR from eutrophic waters through clarification and filtration followed by adsorption on granular activated carbon

RESUMO Usualmente, o tratamento convencional de águas com altas densidades de cianobactérias e concentração de cianotoxinas não garante efluente consoante o padrão de potabilidade vigente (1,0 µg.L-1 de microcistina). Etapas adicionais fazem-se necessárias, destacando-se a adsorção por carvão ativado granular ou pulverizado. Neste contexto, o objetivo geral deste trabalho foi avaliar em escala de bancada a remoção de microcistina em água natural por adsorção em colunas de carvão ativado granular de casca de coco, após as etapas de clarificação e filtração em areia. Os resultados mostraram que o transpasse no carvão de maior granulometria ocorreu em menor tempo de contato (2 h), quando comparado ao de menor granulometria. Tais resultados abrem perspectiva de emprego em escala real por garantir efluente com concentração inferior ao que estabelece a Portaria 2914 por mais tempo e utilizando menor massa de carvão.

ABSTRACT Conventional treatment process of natural waters with high densities of cyanobacteria and cyanotoxins usually presents low efficiency according to the present drinking water standard (maximum permissible value of 1.0 µg.L-1 of microcystin). Additional steps, such as activated carbon, commonly become necessary to achieve the maximum permissible value of microcystin (1.0 µg.L-1) set up by Brazilian Drinking Water Regulation 2914. In this context, the main objective of this work was to evaluate microcystin removal from natural waters by means of two granular activated carbons after clarification and sand filtration in bench scale. The results pointed out that the breakthrough happened in activated carbon with highest grain sizes in lower contact time (2 h) , when compared with that with smaller grain sizes. These results open the perspective of an application of the activated carbon in actual scale, assuring the treated water quality in compliance with the Brazilian Drinking Water Standards Regulation 2914.

Degradation of cyanotoxins (microcystin) in drinking water using photoelectrooxidation / Degradação de cianotoxinas (microcistinas) em água potável aplicando fotoeletrooxidação

The discharge of sewage and industrial effluents containing high concentrations of pollutants in water bodies increases eutrophication. Cyanobacteria, some of the organisms whose growth is promoted by high nutrient concentrations, are resistant and produce several types of toxins, known as cyanotoxins, highly harmful to human beings. Current water treatment systems for the public water supply are not efficient in degradation of toxins. Advanced oxidation processes (AOP) have been tested for the removal of cyanotoxins, and the results have been positive. This study examines the application of photoelectrooxidation in the degradation of cyanotoxins (microcystins). The performance of the oxidative processes involved was evaluated separately: Photocatalysis, Electrolysis and Photoelectrooxidation. Results showed that the electrical current and UV radiation were directly associated with toxin degradation. The PEO system is efficient in removing cyanotoxins, and the reduction rate reached 99%. The final concentration of toxin was less than 1 µg/L of microcystin in the treated solution.

A descarga de esgotos e efluentes industriais contendo altas concentrações de poluentes nos corpos d'água aumenta a eutrofização. As cianobactérias, são organismos cujo crescimento é promovido por concentrações elevadas de nutrientes, são resistentes e produzem vários tipos de toxinas conhecidas, como cianotoxinas, altamente prejudiciais para os seres humanos. Os sistemas atuais de tratamento de água para o abastecimento público de água não são eficientes na degradação destas toxinas. Processos oxidativos avançados (POA) foram testados para a remoção de cianotoxinas, e os resultados têm sido positivos. Este estudo avalia o processo de fotoeletrooxidação (FEO) na degradação de cianotoxinas (microcistinas). Foi avaliado o desempenho dos processos envolvidos separadamente: fotocatalisis, eletrólise e fotoeletrooxidação. Os resultados mostram que a potencia da radiação UV e da corrente elétrica estão diretamente associados com a degradação de toxinas. O sistema de FEO é eficiente na remoção de cianotoxinas e a redução foi de 99%. A concentração final de toxina foi inferior a 1 g / L de microcistina na solução tratada.

Sensitivity of salad greens (Lactuca sativa L. and Eruca sativa Mill.) exposed to crude extracts of toxic and non-toxic cyanobacteria / Sensibilidade de hortaliças (Lactuca sativa L. e Eruca sativa Mill.) à exposição de extratos brutos de cianobactéria tóxica e não tóxica

We evaluated the effect of crude extracts of the microcystin-producing (MC+) cyanobacteria Microcystis aeruginosa on seed germination and initial development of lettuce and arugula, at concentrations between 0.5 μg.L–1 and 100 μg.L–1 of MC-LR equivalent, and compared it to crude extracts of the same species without the toxin (MC–). Crude extracts of the cyanobacteria with MC (+) and without MC (–) caused different effects on seed germination and initial development of the salad green seedlings, lettuce being more sensitive to both extracts when compared to arugula. Crude extracts of M. aeruginosa (MC+) caused more evident effects on seed germination and initial development of both species of salad greens than MC–. Concentrations of 75 μg.L–1 and 100 μg.L–1 of MC–LR equivalent induced a greater occurrence of abnormal seedlings in lettuce, due to necrosis of the radicle and shortening of this organ in normal seedlings, as well as the reduction in total chlorophyll content and increase in the activity of the antioxidant enzyme peroxidase (POD). The MC– extract caused no harmful effects to seed germination and initial development of seedlings of arugula. However, in lettuce, it caused elevation of POD enzyme activity, decrease in seed germination at concentrations of 75 μg.L–1 (MC-75) and 100 μg.L–1 (MC-100), and shortening of the radicle length, suggesting that other compounds present in the cyanobacteria extracts contributed to this result. Crude extracts of M. aeruginosa (MC–) may contain other compounds, besides the cyanotoxins, capable of causing inhibitory or stimulatory effects on seed germination and initial development of salad green seedlings. Arugula was more sensitive to the crude extracts of M. aeruginosa (MC+) and (MC–) and to other possible compounds produced by the cyanobacteria.

Analisamos os efeitos de extratos brutos da cianobactéria M. aeruginosa, produtora de microcistinas (MC+), na germinação de sementes e no desenvolvimento de plântulas de alface e rúcula, em concentrações de 0,5 a 100 μg.L–1de MC–LR equivalente e comparamos com extrato brutos da mesma espécie sem a toxina (MC–). Extratos brutos de cianobactérias com MC (+) e sem MC (–) causaram efeitos diferentes na germinação de sementes e desenvolvimento de plântulas de hortaliças, sendo que a alface apresentou maior sensibilidade a ambos os extratos comparando-se com a rúcula. Extratos brutos de M. aeruginosa (MC+) causaram efeitos mais evidentes sobre a germinação de sementes e desenvolvimento de plântulas de hortaliças do que os (MC–). Concentrações de 75 e 100 μg.L–1 de MC–LR equivalente induziram maior ocorrência de plântulas anormais na alface devido ao aparecimento de necrose na radícula e seu encurtamento nas plântulas normais, bem como a redução no teor de clorofila total e aumento na atividade da enzima antioxidante peroxidase (POD). O extrato (MC–) não provocou efeitos inibitórios na germinação de sementes e desenvolvimento de plântulas para a rúcula, no entanto, provocou elevação da atividade da enzima POD, redução na germinação de sementes nas concentrações de 75 e 100 μg.L–1, e no comprimento da radícula na alface, sugerindo a ação de outros compostos presentes nos extratos da cianobactéria. Extratos brutos de M. aeruginosa (MC–) podem conter outros compostos além de cianotoxinas capazes de provocar efeitos inibitórios ou estimulatórios na germinação de sementes e no desenvolvimento de plântulas de hortaliças. A rúcula apresentou menor sensibilidade aos extratos brutos de M. aeruginosa (MC+) e (MC–) e outros possíveis compostos produzidos por estas cianobactérias.

Degradation of cyanotoxins (microcystin) in drinking water using photoelectrooxidation

p>The discharge of sewage and industrial effluents containing high concentrations of pollutants in water bodies increases eutrophication. Cyanobacteria, some of the organisms whose growth is promoted by high nutrient concentrations, are resistant and produce several types of toxins, known as cyanotoxins, highly harmful to human beings. Current water treatment systems for the public water supply are not efficient in degradation of toxins. Advanced oxidation processes (AOP) have been tested for the removal of cyanotoxins, and the results have been positive. This study examines the application of photoelectrooxidation in the degradation of cyanotoxins (microcystins). The performance of the oxidative processes involved was evaluated separately: Photocatalysis, Electrolysis and Photoelectrooxidation. Results showed that the electrical current and UV radiation were directly associated with toxin degradation. The PEO system is efficient in removing cyanotoxins, and the reduction rate reached 99%. The final concentration of toxin was less than 1 µg/L of microcystin in the treated solution. /p>

p>A descarga de esgotos e efluentes industriais contendo altas concentrações de poluentes nos corpos d'água aumenta a eutrofização. As cianobactérias, são organismos cujo crescimento é promovido por concentrações elevadas de nutrientes, são resistentes e produzem vários tipos de toxinas conhecidas, como cianotoxinas, altamente prejudiciais para os seres humanos. Os sistemas atuais de tratamento de água para o abastecimento público de água não são eficientes na degradação destas toxinas. Processos oxidativos avançados (POA) foram testados para a remoção de cianotoxinas, e os resultados têm sido positivos. Este estudo avalia o processo de fotoeletrooxidação (FEO) na degradação de cianotoxinas (microcistinas). Foi avaliado o desempenho dos processos envolvidos separadamente: fotocatalisis, eletrólise e fotoeletrooxidação. Os resultados mostram que a potencia da radiação UV e da corrente elétrica estão diretamente associados com a degradação de toxinas. O sistema de FEO é eficiente na remoção de cianotoxinas e a redução foi de 99%. A concentração final de toxina foi inferior a 1 g / L de microcistina na solução tratada. /p>

Biodegradation of [D-Leu1] microcystin-LR by a bacterium isolated from sediment of Patos Lagoon estuary, Brazil

Background Toxic cyanobacterial blooms are recurrent in Patos Lagoon, in southern Brazil. Among cyanotoxins, [D-Leu1] microcystin-LR is the predominant variant whose natural cycle involves water and sediment compartments. This study aimed to identify and isolate from sediment a bacterial strain capable of growing on [D-Leu1] microcystin-LR. Sediment and water samples were collected at two distinct aquatic spots: close to the Oceanographic Museum (P1), in Rio Grande City, and on São Lourenço Beach (P2), in São Lourenço do Sul City, southern Brazil. Methods [D-Leu1] microcystin-LR was isolated and purified from batch cultures of Microcystis aeruginosastrain RST9501. Samples of water and sediment from Rio Grande and São Lourenço do Sul were collected. Bacteria from the samples were allowed to grow in flasks containing solely [D-Leu1] microcystin-LR. This strain named DMSX was isolated on agar MSM with 8 g L1 glucose and further purified on a cyanotoxin basis growth. Microcystin concentration was obtained by using the ELISA immunoassay for microcystins whereas bacterial count was performed by epifluorescence microscopy. The genus Pseudomonas was identified by DNA techniques. Results Although several bacterial strains were isolated from the samples, only one, DMXS, was capable of growing on [D-Leu1] microcystin-LR. The phylogenetic analysis of the 16S rRNA gene from DMXS strain classified the organism as Pseudomonas aeruginosa. DMXS strain incubated with [D-Leu1] microcystin-LR lowered the amount of toxin from 1 g.L1 to 0.05 g.L1. Besides, an increase in the bacterial countfrom 71×105 bacteria.mL1 to 117×105 bacteria.mL1was observed along the incubation. Conclusions The use of bacteria isolated from sediment for technological applications to remove toxic compounds is viable. Studies have shown that sediment plays an important role as a source of bacteria capable of degrading cyanobacterial toxins. This is the first Brazilian report on a bacteriumof the genus Pseudomonasthat can degrade [D-Leu1] microcystin-LR, the most frequent microcystin variant in Brazilian freshwaters.

Biodegradation of [D-Leu1] microcystin-LR by a bacterium isolated from sediment of Patos Lagoon estuary, Brazil

Background: Toxic cyanobacterial blooms are recurrent in Patos Lagoon, in southern Brazil. Among cyanotoxins, [D-Leu1] microcystin-LR is the predominant variant whose natural cycle involves water and sediment compartments. This study aimed to identify and isolate from sediment a bacterial strain capable of growing on [D-Leu1] microcystin-LR. Sediment and water samples were collected at two distinct aquatic spots: close to the Oceanographic Museum (P1), in Rio Grande City, and on São Lourenço Beach (P2), in São Lourenço do Sul City, southern Brazil. Methods: [D-Leu1] microcystin-LR was isolated and purified from batch cultures of Microcystis aeruginosastrain RST9501. Samples of water and sediment from Rio Grande and São Lourenço do Sul were collected. Bacteria from the samples were allowed to grow in flasks containing solely [D-Leu1] microcystin-LR. This strain named DMSX was isolated on agar MSM with 8 g L−1 glucose and further purified on a cyanotoxin basis growth. Microcystin concentration was obtained by using the ELISA immunoassay for microcystins whereas bacterial count was performed by epifluorescence microscopy. The genus Pseudomonas was identified by DNA techniques. Results; Although several bacterial strains were isolated from the samples, only one, DMXS, was capable of growing on [D-Leu1] microcystin-LR. The phylogenetic analysis of the 16S rRNA gene from DMXS strain classified the organism as Pseudomonas aeruginosa. DMXS strain incubated with [D-Leu1] microcystin-LR lowered the amount of toxin from 1 μg.L−1 to < 0.05 μg.L−1. Besides, an increase in the bacterial count–from 71 × 105 bacteria.mL−1 to 117 × 105 bacteria.mL−1–was observed along the incubation. Conclusions: The use of bacteria isolated from sediment for technological applications to remove toxic compounds is viable. Studies have shown that sediment plays an important role as ...

Growth and microcystin production of a Brazilian Microcystis aeruginosa strain (LTPNA 02) under different nutrient conditions

Cyanobacteria are prokaryotic and photosynthetic organisms, which can produce a wide range of bioactive compounds with different properties; including a variety of toxic compounds, also known as cyanotoxins. In this work, we describe the isolation of seven cyanobacterial strains from two reservoirs in São Paulo State, Brazil. Seven different chemical variants of microcystins (MC-RR, MC-LR, MC-YR, MC-LF, MC-LW, and two demethylated variants, dm-MC-RR and dm-MC-LR) were detected in three of the ten isolated strains. One particular Microcystis aeruginosa strain (LTPNA 02) was chosen to evaluate its growth by cell count, and its toxin production under seven different nutritional regimes. We observed different growth behaviors in the logarithmic growth period for only three experiments (p < 0.05). The total growth analysis identified four experiments as different from the control (p < 0.01). Three microcystin variants (MC-RR, MC-LR and MC-YR) were quantified by liquid chromatography-tandem mass spectrometry. At the experimental end, the toxin content was unchanged when comparing cell growth in ASM-1 (N:P = 1), MLA and BG-11 (N:P = 10) medium. In all other experiments, the lowest microcystin production was observed from cells grown in Bold 3N medium during the exponential growth phase. The highest microcystin content was observed in cultures using BG-11(N:P = 100) medium.

Development and optimization of ultrasensitive homogenous immunoassay for microcystin-LR / 中国药理学与毒理学杂志

OBJECTIVE Apolyclonalantibody-basedhomogeneouschemiluminescenceimmunoas-say was developed and optimized using AlphaLISA technology for the quantitative detection of microcys-tin-LR(MC-LR)inwatersamples.METHODS Thismethodwasbasedonacompetitivemodelin which an immune complex was formed from the ingegral binding of artificial MC-LR antigen-coated lumi-nescene beads,free MC-LR standards or sa mples,antibody and biotinylated second antibody.Next sensor bead were added that approached the i mmune co mplex through biotin-streptavidin interaction. With the exciting light,the energy was passed from the sensor luminescer before a special emission light could be observed.To opti mize the reaction conditions,working dilutions of polyclonal antibody and bioti-nylated second antibody were assayed while the effect of buffer syste ms and ti me of each reaction were evaluated.RESULTS Maininfluencingfactorsoftheassaywerediscussedasworkingdilutionsofpoly-clonal antibody and biotinylated goat anti rabbit IgG,assay buffer and reacting ti me.After opti mization of reaction conditions,MC-LR AlphaLISA could be finished in 40 min,with a sensitivity of 0.006 μg·L-1 and a dynamic range of 0.006 -5 μg·L-1 .The coefficient of variation was below 10% and average recovery was 1 07.7%.Moreover,the cross reactivity rates of MC-RR and MC-RY to MC-LR were 13.2%and0.91%,respectively.CONCLUSION Thismethodishighlysensitiveandspecific,time-saving and quite suitable for high throughput determination of MC-LR water samples.

A Label-free Immunosensor for Microcystins-LR Based on Graphene and Gold Nanocage / 分析化学

A label-free electrochemical immunosensor using hollow structure nanomaterials based on its ordered porous and big surface area was designed. Au nanocage, with good conductivity, catalysis, and biocompatibility, was prepared and modified on the surface of glassy carbon electrode with graphene to immobilize antibody of microcystin directly. In the absence of microcystin, biosensor can obtain high current response signal of electrochemical probe ( [ Fe( CN) 6 ] 3-/4-. When microcystin was combined with its antibody specifically, the charge density and mass transfer resistance on the surface of electrode increased, resulting in a decrease of the corresponding peak current of [ Fe ( CN ) 6 ] 3-/4-. This change was in proportion to the concentration of microcystin indirectly. Experiment conditions such as cultivation time of antigen and concentration of antibody were optimized. The results showed wide linear range of 0. 05 μg/L-1. 0 mg/L and the detection limit of 0. 017 ng/mL. This sensor has good stability and simple production procedure. This sensor provides a new and simple means for the ultrasensitive determination of microcystins in real water samples.

Presença da toxina microcistina em água, impactos na saúde pública e medidas de controle / Microcystin toxin in the presence of water, public health impact and control measures

As cianobactérias constituem um grupo de micro-organismos procariontes encontrado em ambientes aquáticos, os quais vêm sendo pesquisado devido à capacidade de produzir toxinas que causam grandes impactos à saúde pública e ambiental. A ocorrência de florações desses micro-organismos em reservatórios de água utilizada para abastecimento público tem sido frequente e prejudicado os usos múltiplos da água. Algumas cepas produzem florações nocivas liberando compostos neurotóxicos, hepatotóxicos ou irritantes à pele de seres humanos e animais, podendo ocasionar intoxicação e morte. A literatura reporta a ocorrência de um acidente em Caruaru, Pernambuco, onde faleceram 65 pacientes que faziam hemodiálise, devido à presença de microcistina-LR na água que consumiram. Esse estudo objetivou realizar uma revisão sobre a presença da toxina microcistina em água, os impactos e medidas de controle. Foram relatados os principais métodos utilizados para a remoção e quantificação da microcistina em água, bem como sua relação com a saúde humana.

Cyanobacteria are a group of prokaryotic microorganisms found in aquatic environments, which have been researched because of the ability to produce toxins that cause major public health impacts and environmental. The occurrence of seaweed buddings in reservoirs used for public supplying has been frequent, and has affected the multiple uses of the drinking water. Some strains of seaweed, in special the cyanobacterial, can produce toxins as the microcystins, which are responsible for the intoxication and death of animals and humans.The literature reports the occurrence of an accident in Caruaru, Pernambuco, where he died 65 hemodialysis patients who were due to the presence of microcystin-LR in water. This study aimed to perform a review of the presence of the toxin microcystin in water, impacts and control measures. Reported were the main methods used for the removal and quantification of microcystins in water and its relation to human health.

Potencial de biodegradação de microcistinas por microrganismos / Biodegradation potential of microcystins by microorganisms

Para minimizar os problemas relacionados à ocorrência de cianobactéria em águas destinadas ao consumo humano há necessidade de se realizar estudos de alternativas técnicas de tratamento com destaque aos biofilmes com potencial de degradação de microcistinas (MC). O presente trabalho teve como objetivo avaliar o potencial de degradação de MC pela bactéria Sphingosinicella microcystinivorans B9, diferentes cepas de leveduras e bactérias probióticas. O teste foi efetuado com extrato de MC e diferentes quantidades de biovolume e densidade celular dos microrganismos. Os tratamentos foram mantidos a 27ºC com rotação de 100 rpm e as amostras para análise de MC e contagem dos microrganismos foram retiradas após 0 e 96 horas de contato. A bactéria B9 apresentou maior degradação de MC, chegando a 98% após 96 horas.

To minimize problems related to the occurrence of cyanobacteria in water for human consumption there is need to investigate alternative treatment techniques with emphasis on biofilms with the potential degradation of microcystins (MC). This study aimed to evaluate the potential degradation of MC by bacteria Sphingosinicella microcystinivorans B9, different strains of yeast and probiotic bacteria. The test was carried out with the extract obtained from strain Microcystis sp. In the tests biomass and cultures of microorganisms were used and the treatments were maintained at 27ºC with 100 rpm. Samples for analysis of MC and for counting the microorganisms were collected at 0 and 96 hours. The bacterium B9 presented the highest potential of degradation of MC reaching 98% after 96 hours.

Effects of microcystin exposure to open field behavior and cognitive function of rats / 中华行为医学与脑科学杂志

ObjectiveTo observe the potential effects of microcystin-LR (MC-LR) to open field behaviors and cognitive functions of rats after low-dose and 60 days exposure.Methods20 SD male rats (4 weeks old) were grouped into control ( double distilled water),0.2,1.0 and 5.0 μg/kg groups by random number table.Rats were exposed to microcystin-LR intragastrically every two days for 60 d.Open fields and Morris water maze were employed to observe the spontaneous behavior and spatial learning and memory capacity of rats.ResultsFor each group,the duration in the central area of open field were ( 8.86 ± 3.38 ) s,( 3.09 ± 1.22 ) s,( 1.68 ± 0.24) s,(1.22 ±0.93) s,frequencies in central area were (4.80 ± 1.16) times,(4.40 ± 1.91 )times,( 1.40 ±0.23)times,(3.80 ± 1.02 ) times,movement duration were ( 137.30 ± 5.25 ) s,( 122.97 ± 9.50) s,( 108.86 ± 6.38 ) s,( 129.35 ± 9.40) s,the escape latency were ( 23.17 ± 4.28 ) s,(77.00 ± 8.31 ) s,(59.00 ± 11.89) s,( 63.80 ±16.09) s,respectively.Compared to control,the duration in the central area of open field decreased and escape latency increased significantly (P ＜ 0.05 ) in all the MC-LR treated groups; and frequencies in central area and movement duration of 1.0 μg/kg treated rats decreased significantly.No significant differences were observed between expsoured group and control group in spacial probe tests(P＞0.05).ConclusionMC-LR exerts effects on the spontaneous behavior and spatial cognitive ability of rats.The further study on neurobehavior effects of MC-LR is necessary.