Cyanobacteria In Water Research Articles

Potencial de biodegradação de microcistinas por microrganismos

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.

Toxic cyanobacterial breakthrough and accumulation in a drinking water plant: A monitoring and treatment challenge

The detection of cyanobacteria and their associated toxins has intensified in recent years in both drinking water sources and the raw water of drinking water treatment plants (DWTPs). The objectives of this study were to: 1) estimate the breakthrough and accumulation of toxic cyanobacteria in water, scums and sludge inside a DWTP, and 2) to determine whether chlorination can be an efficient barrier to the prevention of cyanotoxin breakthrough in drinking water. In a full scale DWTP, the fate of cyanobacteria and their associated toxins was studied after the addition of coagulant and powdered activated carbon, post clarification, within the clarifier sludge bed, after filtration and final chlorination. Elevated cyanobacterial cell numbers (4.7×106cells/mL) and total microcystins concentrations (up to 10mg/L) accumulated in the clarifiers of the treatment plant. Breakthrough of cells and toxins in filtered water was observed. Also, a total microcystins concentration of 2.47μg/L was measured in chlorinated drinking water. Cyanobacterial cells and toxins from environmental bloom samples were more resistant to chlorination than results obtained using laboratory cultured cells and dissolved standard toxins.

Effect of chlorination on the cell integrity of two noxious cyanobacteria and their releases of odorants

The effect of chlorination on cell integrity and release of metabolites of two noxious cyanobacteria, a β-cyclocitral producer— Microcystis aeruginosa —and a geosmin producer— Anabaena circinalis —was investigated. Photos from a scanning electron microscope revealed that Microcystis cell surfaces were deformed after chlorination, and filamentary Anabaena cells were ruptured at the junction of vegetative cell units. Chlorination experiments indicated that both cyanobacteria are susceptible to attack by chlorine. A first-order decay model was used to simulate the cell-rupture kinetics during chlorination. Using laboratory cultures, the observed rate constants are 670–1,100 M−1 s−1 for M. aeruginosa , which are 1.3–5.0 times as large as those for A. circinalis . For unfiltered Microcystis -laden reservoir waters, a broader range of rate constants, 70–590 M−1 s−1, were obtained. The rate constant was reduced in more eutrophic water, due probably to the competition of chlorine with other cyanobacteria in water. Geosmin was rapidly released into water immediately after the Anabaena cells were ruptured. However, a portion of geosmin remained cell-bound. For Microcystis , the total β-cyclocitral concentration decreased quickly during chlorination in most cases. It is speculated that the enzymes leading to the formation of β-cyclocitral were inhibited by chlorine, thus causing a sudden reduction of β-cyclocitral in the system.

Dynamic Cytotoxic Response to Microcystins Using Microelectronic Sensor Arrays

Microcystins are bioactive metabolites produced by cyanobacteria in water. These cyclic heptapeptides have caused public health concern worldwide. By interfering with cellular phosphorylation and signaling, microcystins can cause acute and chronic liver diseases. Therefore, the World Health Organization (WHO) has set the provisional drinking water guideline value at 1.0 microg/L for microcystin-LR (free plus cell-bound). Microcystins do not readily cross cell membranes in in vitro cell-based assays, except for those using freshly isolated hepatocytes. However, the sensitivity of in vitro cell-based assays is not adequate for testing samples at low environmental concentrations. Hence, there is a need to develop a sensitive and stable cytotoxicity assay for use in environmental studies. On the basis of the observation that microcystin-LR can be transported by the liver-specific members of the organic anion transporting polypeptides (OATPs), we investigated the potential of using an OATP1B3-expressing cell line in a cytotoxicity assay for microcystins. Using a novel cell electronic sensing system (RT-CES), we were able to monitor the real-time, dynamic cytotoxic response to microcystins at microgram per liter concentrations. We demonstrated that the cytotoxicity of the most common microcystins, -LR, -YR, -RR, -LF, and -LW, was mediated by OATP1B3 transporters. Microcystin-LF is the most potent toxin among the five congeners. In conclusion, we have established a highly automated, real-time, sensitive, and stable assay for measuring microcystin cytoxicity.

Cyanobacterial diversity in Salar de Huasco, a high altitude saline wetland in northern Chile: an example of geographical dispersion?

The diversity of Cyanobacteria in water and sediment samples from four representative sites of the Salar de Huasco was examined using denaturing gradient gel electrophoresis and analysis of clone libraries of 16S rRNA gene PCR products. Salar de Huasco is a high altitude (3800 m altitude) saline wetland located in the Chilean Altiplano. We analyzed samples from a tributary stream (H0) and three shallow lagoons (H1, H4, H6) that contrasted in their physicochemical conditions and associated biota. Seventy-eight phylotypes were identified in a total of 268 clonal sequences deriving from seven clone libraries of water and sediment samples. Oscillatoriales were frequently found in water samples from sites H0, H1 and H4 and in sediment samples from sites H1 and H4. Pleurocapsales were found only at site H0, while Chroococcales were recovered from sediment samples of sites H0 and H1, and from water samples of site H1. Nostocales were found in sediment samples from sites H1 and H4, and water samples from site H1 and were largely represented by sequences highly similar to Nodularia spumigena. We suggest that cyanobacterial communities from Salar de Huasco are unique - they include sequences related to others previously described from the Antarctic, along with others from diverse, but less extreme environments.

Detection and estimation of potentially toxic cyanobacteria in raw water at the drinking water treatment plant by in vivo fluorescence method

In vivo fluorescence methods have been accepted as a quick, simple, and useful tool for quantification of phytoplankton organisms. In this paper, we present a case study in which fluorescence methods were employed for the selective detection of potentially toxic cyanobacteria in raw water at the drinking water treatment plant. The occurrence of cyanobacteria in the drinking water reservoir and in raw water was monitored by phycocyanin fluorescence measurements and by standard methods for phytoplankton quantification (cell counts, chlorophyll a). A special attention was paid to the most critical parts of the season — spring recruitment of cyanobacteria from sediment to water column and autumn bloom collapse. All methods showed similar patterns within the season. Phycocyanin fluorescence was found to be a simple and sensitive indicator of cyanobacteria in water and can serve as a tool that can provide an early warning about the presence of potentially toxic cyanobacterial metabolites in water.

Seasonal variation in standing crops of bloom-forming cyanobacteria in water and sediment in Lake Yogo, Japan

Seasonal variation in standing crops of bloom-forming cyanobacteria in water and sediment in Lake Yogo, Japan

Evaluation of different DNA sampling techniques for the application of the real-time PCR method for the quantification of cyanobacteria in water

To evaluate different types of sample storage and DNA extraction techniques for the real-time PCR quantification of cyanobacteria in water. Two different filter types for the cell harvest of Microcystis sp. and Planktothrix spp. that were either freeze-dried or stored frozen, and two different methods for DNA extraction were compared. DNA extraction was achieved by standard phenol-chloroform extraction or by a faster commercially available purification kit (DNeasy, QIAGEN). In general there was good agreement between the cell number equivalents of phycocyanin (PC) genotypes that were estimated using the Taq nuclease assay (TNA) between both filter types and the storing of samples. The standard DNA extraction procedure gave higher numbers of PC genotypes when compared with the DNeasy procedure. TNA results obtained from Planktothrix from natural samples extracted with the standard procedure revealed a significant correlation with the cell numbers estimated via the microscope. Freeze-drying of samples gives quantifiable data. The standard DNA extraction is considered to be the most reliable and accurate, although the DNeasy procedure is useful for early warning monitoring. Application of quantitative genotype analysis in cyanobacteria from freeze-dried samples collected during recent and past sampling programmes.

A Simple In Vivo Fluorescence Method for the Selective Detection and Quantification of Freshwater Cyanobacteria and Eukaryotic Algae

A method for the rapid detection of cyanobacteria (blue-green algae) and their differentiation from eukaryotic algae in natural phytoplankton assemblages is presented. Fluorescence emission of photosynthetic pigments at 670 nm was measured using a microplate fluorescence reader when excited at two different wavelengths - 485 nm and 590 nm. The ratio of fluorescence excited at these wavelengths (590 nm/485 nm) was proportional to the ratio of cyanobacteria and eukaryotic algae, which was determined by the in situ spectrofluorometer for the phytoplankton quantification. The fluorescence intensity was equal to the total chlorophyll-a content. These two fluorescence values can provide the first warning on a development of potentially toxic cyanobacteria in water.

Proliferaciones algales nocivas de cianobacterias (Oscillatoriaceae) y dinoflagelados (Gymnodiniaceae) en el Golfo de Nicoya, Costa Rica

Recently, the Pacific coast of Costa Rica has experienced an increase in both magnitude and frequency of harmful algae blooms (HAB). The lack of data regarding the dynamics of these events in the area, and the species of microalgae that produce them, are themes of great interest. The blooms have produced negative impacts on fishery resources and on human health in Costa Rica. In May 2002 a HAB left a large number of dead fish along the central Pacific coast. Water samples were collected using a phytoplankton net and fixed for subsequent processing by electron microscopy. In addition, a one liter sample of surface water was taken for later cell count. In the observed HAB, the dominating organisms found were the cyanobacteria Trichodesmiun erythraeum surrounded by high concentrations of Gram - bacteria and the dinoflagellate Cochlodinium cf. polykrikoides. T. erythraeum, is one of the most important N2 fixing cyanobacteria in marine waters that has been associated with HAB events in diverse parts of the world as well as with symptoms that produce contact dermatitis and other discomforts. C. cf. polykrikoides is a dinoflagellete associated with fish kills; although the type of associated toxins are unknown. In a national newspaper 17 cases of intoxication in humans were reported during this same period, which presented respiratory disorders and burning of the eyes. This is the first report in Costa Rica where a cyanobacteria and a dinoflagellate were observed together producing HAB.

Behavior of filamentous cyanobacterium Anabaena spp. in water column and its cellular characteristics

From a practical viewpoint, cyanobacteria have two opposite aspects: one is that some of the species participate in water bloom, and the other is that they may be used in agriculture as a biofertilizer. Akinete, a dormant cell, is the key to the engineering analysis of both cases. In order to analyze the behavior of cyanobacteria in water, Anabaena cylindrica, a filamentous cyanobacterium, was investigated in terms of the behavior of algal biomass in a water column and its characteristics in akinete formation. The algal culture transferred to a glass cylinder settled down initially and then floated to the surface of the water column, forming an algal mat due to oxygen bubbles generated extracellularly by photosynthesis. The differentiation of vegetative cells into akinetes was not induced by light limitation but iron depletion. Akinetes tended to separate from trichomes and settle down because their density is higher than that of water. This phenomenon suggests an operational method for removing the source of water bloom from an aquatic environment, or harvesting akinetes as the seed of biofertilizers.

An electronic nose system for monitoring the quality of potable water

A measurement system has been developed for the testing of cyanobacteria in water, and it consists of three main stages: the odour sampling system, an electronic nose (e-nose) and a CellFacts instrument that analyses liquid samples. The e-nose system, which employs an array of six commercial odour sensors, has been used to monitor not only different strains but also the growth phase of cyanobacteria (i.e. blue-green algae) in water over a 40-day period. Principal components analysis (PCA), multi-layer perceptron (MLP), learning vector quantisation (LVQ) and Fuzzy ARTMAP were used to analyse the response of the sensors. The optimal MLP network was found to classify correctly 97.1% of the unknown nontoxic and 100% of the unknown toxic cyanobacteria. The optimal LVQ and Fuzzy ARTMAP algorithms were able to classify 100% of both strains of cyanobacteria samples. The accuracy of MLP, LVQ and Fuzzy ARTMAP in terms of predicting four different growth phases of toxic cyanobacteria was 92.3%, 95.1% and 92.3%, respectively. These results show the potential application of neural network based e-noses to test the quality of potable water as an alternative to instruments, such as liquid chromatography or optical microscopy.

Classification of the strain and growth phase of cyanobacteria in potable water using an electronic nose system

An electronic nose comprising an array of six commercial odour sensors has been used to monitor not only different strains, but also the growth phase, of cyanobacteria which is normally called blue green algal. A series of experiments were carried out to analyse the nature of two closely related strains of cyanobacteria, Microcystis aeruginosa PCC 7806 that produces a toxin and PCC 7941 that does not. The authors have constructed a measurement system for the testing of the cyanobacteria in water over a period of up to 40 days. After some pre-processing to remove the variation associated with running the electronic nose in ambient air, the two different strains, and their growth phase, with principal component, were classified analysis, multilayer perceptron (MLP), learning vector quantisation (LVQ), and fuzzy ARTMAP. The optimal MLP network was found to classify correctly 97.1% of unknown non-toxic and 100% of unkhown toxic cyanobacteria. The optimal LVQ and fuzzy ARTMAP algorithms were able to classify 100% of both strains of cyanobacteria. The accuracy of MLP, LVQ and fuzzy ARTMAP algorithms with the four different growth phases of toxic cyanobacteria was 92.3%, 95.1% and 92.3%, respectively.

Toxic cyanobacteria in water. A guide to their public health consequences, monitoring, and management

Toxic cyanobacteria in water. A guide to their public health consequences, monitoring, and management

Toxic Cyanobacteria in Water, edited by Ingrid Chorus and Jamie Bartram

Toxic Cyanobacteria in Water, edited by Ingrid Chorus and Jamie Bartram

Quantification of toxic cyanobacteria in water by use of competitive PCR followed by sequence-specific labeling of oligonucleotide probes.

A complete nucleic-acid-based assay which consists of sample preparation, DNA amplification, and chromogenic detection was developed for quantifying potential toxin-producing cyanobacteria of interest to the public. The sample preparation strategy involves the same solid phase for cell concentration and DNA purification. For the detection step, we used a combination of competitive PCR amplification, sequence-specific labeling of oligonucleotide probes, hybridization of the labeled oligonucleotides to immobilized complements and, finally, chromogenic detection. The complete assay was tested with water containing toxin-producing cyanobacteria belonging to the genus Microcystis. A detection limit of 100 cells/ml and a quantitative range of more than 3 orders of magnitude were obtained. This approach can easily be adapted to a wide range of bacterial species and has the potential for simultaneous detection and quantitation of several different target organisms by a single assay.

Low-molecular-weight carbohydrate biosynthesis and the distribution of cyanobacteria (blue-green algae) in marine environments

Rates of accumulation of low-molecular-weight carbohydrates have been measured for a range of cyanobacteria subjected to hyperosmotic stress (upshock). Synthesis of the disaccharides sucrose and trehalose was more rapid than that of the heteroside glucosyl-glycerol in all strains. The rates of synthesis of organic solutes may affect the distribution of cyanobacteria in natural saline waters:strains that produce either sucrose or trehalose in response to increased external salinity are often found in brackish habitats where the salinity regime is unstable and rapid organic solute synthesis may be advantageous. In contrast, cyanobacteria that synthesize glucosyl-glycerol are more commonly isolated from environments of less variable salinity.