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Current Trend of Metagenomic Data Analytics for Cyanobacteria Blooms  [PDF]
JianDong Huang, Huiru (Jane) Zheng, Haiying Wang
Journal of Geoscience and Environment Protection (GEP) , 2017, DOI: 10.4236/gep.2017.56018
Abstract:
Cyanobacterial harmful algal blooms are a major threat to freshwater eco-systems globally. To deal with this threat, researches into the cyanobacteria bloom in fresh water lakes and rivers have been carried out all over the world. This review presents an overlook of studies on cyanobacteria blooms. Conventional studies mainly focus on investigating the environmental factors influencing the blooms, with their limitation in lack of viewing the microbial community structures. Metagenomics study provides insight into the internal community structure of the cyanobacteria at the blooming, and there are researchers reported that sequence data was a better predictor than environmental factors. This further manifests the significance of the metagenomic study. However, large number of the latter appears to be confined only to present snapshoot of the microbial community diversity and structure. This type of investigation has been valuable and important, whilst an effort to integrate and coordinate the conventional approaches that largely focus on the environmental factors control, and the Metagenomics approaches that reveals the microbial community structure and diversity, implemented through machine learning techniques, for a holistic and more comprehensive insight into the cause and control of Cyanobacteria blooms, appear to be a trend and challenge of the study of this field.
Toxic cyanobacteria blooms in the Lithuanian part of the Curonian Lagoon  [cached]
Aist? Paldavi?ien?,Hanna Mazur-Marzec,Artūras Razinkovas
Oceanologia , 2009,
Abstract: The phenomenon of cyanobacteria (blue-green algae) blooms in the Baltic and the surrounding freshwater bodies has been known for several decades. The presence of cyanobacterial toxic metabolites in the Curonian Lagoon has been investigated and demonstrated for the first time in this work (2006-2007). Microcystis aeruginosa was the most common and widely distributed species in the 2006 blooms. Nodularia spumigena was present in the northern part of the Curonian Lagoon, following the intrusion of brackish water from the Baltic Sea; this is the first time that this nodularin-(NOD)-producing cyanobacterium has been recorded in the lagoon. With the aid of high-performance liquid chromatography (HPLC), four microcystins (MC-LR, MC-RR, MC-LY, MC-YR) and nodularin were detected in 2006. The presence of these cyanobacterial hepatotoxic cyclic peptides was additionally confirmed by enzyme-linked immunosorbent assay (ELISA) and protein phosphatase inhibition assay (PP1). Microcystin-LR, the most frequent of them, was present in every sample at quite high concentrations (from <0.1 to 134.2 μg dm-3). In 2007, no cyanobacterial bloom was recorded and cyanotoxins were detected in only 4% of the investigated samples. A comparably high concentration of nodularin was detected in the northern part of the Curonian Lagoon. In one sample dimethylated MC-RR was also detected (concentration 7.5 μg dm-3).
Do toxic cyanobacteria blooms pose a threat to the Baltic ecosystem?  [cached]
Hanna Mazur-Marzec,Marcin Pliński
Oceanologia , 2009,
Abstract: Cyanobacteria, otherwise known as blue-green algae, are oxygenic, photosynthetic prokaryotes. They occur naturally in many fresh, marine and brackish waters worldwide and play an important role in global carbon and nitrogen cycles. In their long history, cyanobacteria have developed structures and mechanisms that enable them to survive and proliferate under different environmental conditions. In the Baltic Sea, the mass development of cyanobacteria is compounded by a high level of eutrophication. The dominant species in the Baltic, the filamentous Aphanizomenon flos-aquae and Nodularia spumigena, can fix dissolved atmospheric N2, as a result of which they can outcompete other phytoplankton organisms. Heterocystous, filamentous cyanobacteria also make a significant contribution to the internal nutrient loading in the Baltic. The blooms of N. spumigena are of particular concern, as this cyanobacterium produces nodularin (NOD), a hepatotoxic peptide. The concentration of the toxin in the sea is regulated mainly by dilution with uncontaminated water, photolysis, sorption to sediments and microbial degradation. The transfer of the toxin in the Baltic trophic chain through zooplankton, mussels, fish and birds has been reported, but biodilution rather than bioconcentration has been observed. Cyanobacterial blooms are thought to pose a serious threat to the ecosystem. Their harmful effects are related to the occurrence of a high biomass, oxygen depletion, a reduction in biodiversity, and the production of toxic metabolites.
The Role of Cyanobacteria Blooms in Cholera Epidemic in Bangladesh  [PDF]
Md. Sagir Ahmed,Md. Raknuzzaman,Hafeza Akther,Sumaiya Ahmed
Journal of Applied Sciences , 2007,
Abstract: A study was conducted on association of Vibrio cholerae with plankton specially emphasis on cyanobacteria in relation to some physico-chemical parameters in the River Buriganga, Dhaka, from January to December 2002. Monthly abundance of phytoplankton and zooplankton varied from 457 to 14166 and from 169 to 1055 individual L-1, respectively. Monthly average of faecal coliform in water, zooplankton and phytoplankton samples were 3.99x109, 4.54x103 and 4.28x102 (CFU L-1), respectively. During epidemics, toxigenic V. cholerae 01 and 0139 were isolated from the patients as well as from the surface water. V. cholerae 01 and 0139 were also isolated from plankton samples. More over, it was observed that ctx (cholera toxic) positive in water and phytoplankton samples of the river. A bloom of Oscillatoria sp. (1.6x104 individual L-1) occurred in the upper reaches of the River Buriganga in May 2002. Methanol-water extract of bloom sample was analyzed by high performance liquid chromatography with UV detection and Mass Spectrum (MS) detected microcystin-RR. Cyanobacteria are abundant in the aquatic environment of Bangladesh and it was established that V. cholerae maintain a symbiotic relationship with these algae particularly mucilaginous cyanobacteria. During epidemics, patients symptoms included diarrhea, vomiting and hemorrhagic enteritis and in severe cases hemorrhagic diarrhea. So, question has arisen that which is responsible, microcystins or cholera for death of cholera/diarrhea patients in Bangladesh. Future research should be directed to isolate microcystins and cholera toxins from the epidemic areas to clarify the fact.
Toxic cyanobacteria strains isolated from blooms in the Guadiana River (southwestern Spain)
MORENO,ISABEL M; PEREIRA,PAULO; FRANCA,SUSANA; CAMEáN,ANA;
Biological Research , 2004, DOI: 10.4067/S0716-97602004000300006
Abstract: this paper describes the occurrence of toxic cyanobacteria along the guadiana river over its course between mérida and badajoz (extremadura, spain). water sampling for phytoplankton quantification and toxin analysis was carried out regularly between 1999 and 2001 in six different locations, including two shallow, slow-flowing river sites, two streamed river sites and two drinking water reservoirs. the cyanobacterial community differed significantly between these locations, especially during the summer. the predominant genera were microcystis, oscillatoria, aphanizomenon and anabaena. using an elisa assay the total microcystin contents of natural water samples from the most eutrophic locations ranged from 0.10 _ 21.86 mg mcyst-lr equivalent·l-1 in valdelacalzada and 0.10-11.3 μg mcyst-lr equivalent·l-1 in vitonogales, and a seasonal variation of toxin content was observed. the amount of microcystins produced by each strain was determined by elisa assay and the detection and identification of microcystin variants of three toxic strains of microcystis aeruginosa was performed by high performance liquid chromatography (hplc). the analysis of microcystins of the cultured strains revealed that toxin production was variable among different strains of m. aeruginosa isolated either from different blooms or from the same bloom.
Toxic cyanobacteria strains isolated from blooms in the Guadiana River (southwestern Spain)
ISABEL M MORENO,PAULO PEREIRA,SUSANA FRANCA,ANA CAMEáN
Biological Research , 2004,
Abstract: This paper describes the occurrence of toxic cyanobacteria along the Guadiana River over its course between Mérida and Badajoz (Extremadura, Spain). Water sampling for phytoplankton quantification and toxin analysis was carried out regularly between 1999 and 2001 in six different locations, including two shallow, slow-flowing river sites, two streamed river sites and two drinking water reservoirs. The cyanobacterial community differed significantly between these locations, especially during the summer. The predominant genera were Microcystis, Oscillatoria, Aphanizomenon and Anabaena. Using an ELISA assay the total microcystin contents of natural water samples from the most eutrophic locations ranged from 0.10 _ 21.86 mg mcyst-LR equivalent·L-1 in Valdelacalzada and 0.10-11.3 μg mcyst-LR equivalent·L-1 in Vitonogales, and a seasonal variation of toxin content was observed. The amount of microcystins produced by each strain was determined by ELISA assay and the detection and identification of microcystin variants of three toxic strains of Microcystis aeruginosa was performed by high performance liquid chromatography (HPLC). The analysis of microcystins of the cultured strains revealed that toxin production was variable among different strains of M. aeruginosa isolated either from different blooms or from the same bloom.
Diversity of microcystin-producing genotypes in Brazilian strains of Microcystis (Cyanobacteria)
Bittencourt-Oliveira, MC;Oliveira, MC;Pinto, E;
Brazilian Journal of Biology , 2011, DOI: 10.1590/S1519-69842011000100030
Abstract: microcystis kützing ex lemmermann is among the genera of cyanobacteria often associated to toxic blooms with the release of microcystins. a gene cluster codes for microcystin synthetases, which are involved in the biosynthesis of this toxin. the aim of the present study was to investigate the genetic diversity of the mcyb gene, specifically the b1 module, in brazilian strains of microcystis spp. and its microcystin variants. broad genetic diversity was revealed in this region. from the phylogenetic analysis, three clusters were obtained that were not related to the geographic origin or morphospecies of the strains, nor with the variant of the microcystin produced. a group of strains that did not produce microcystins was found, despite the presence of the mcyb1 fragment. eight microcystin isoforms were detected: mc-lr, [d-asp3]-mc-lr, [asp3]-mc-lr, mc-rr, [dha7]-mc-lr, mc-lf, mc-lw and [d-asp3, etadda5]-mc-lh, the latter of which is described for the first time in brazil. moreover, five other variants were not identified and indicate being new.
Hypoxia and cyanobacteria blooms - are they really natural features of the late Holocene history of the Baltic Sea?
L. Zillén ,D. J. Conley
Biogeosciences (BG) & Discussions (BGD) , 2010,
Abstract: During the last century (1900s) industrialized forms of agriculture and human activities have caused eutrophication of Baltic Sea waters. As a consequence, the hypoxic zone in the Baltic Sea has increased, especially during the last 50 years, and has caused severe ecosystem disturbance. Climate forcing has been proposed to be responsible for the reported trends in hypoxia (< 2 mg/l O2) both during the last c. 100 years (since c. 1900 AD) and the Medieval Period. By contrast, investigations of the degree of anthropogenic forcing on the ecosystem on long time-scales (millennial and greater) have not been thoroughly addressed. This paper examines evidence for anthropogenic disturbance of the marine environment beyond the last century through the analysis of the human population growth, technological development and land-use changes in the drainage area. Natural environmental changes, i.e. changes in the morphology and depths of the Baltic basin and the sills, were probably the main driver for large-scale hypoxia during the early Holocene (8000–4000 cal yr BP). We show that hypoxia during the last two millennia has followed the general expansion and contraction trends in Europe and that human perturbation has been an important driver for hypoxia during that time. Hypoxia occurring during the Medieval Period coincides with a doubling of the population (from c. 4.6 to 9.5 million) in the Baltic Sea watershed, a massive reclamation of land in both established and marginal cultivated areas and significant increases in soil nutrient release. The role of climate forcing on hypoxia in the Baltic Sea has yet to be demonstrated convincingly, although it could have helped to sustain hypoxia through enhanced salt water inflows or through changes in hydrological inputs. In addition, cyanobacteria blooms are not natural features of the Baltic Sea as previously deduced, but are a consequence of enhanced phosphorus release from the seabed that occurs during hypoxia.
Spatiotemporal Molecular Analysis of Cyanobacteria Blooms Reveals Microcystis-Aphanizomenon Interactions  [PDF]
Todd R. Miller, Lucas Beversdorf, Sheena D. Chaston, Katherine D. McMahon
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0074933
Abstract: Spatial and temporal variability in cyanobacterial community composition (CCC) within and between eutrophic lakes is not well-described using culture independent molecular methods. We analyzed CCC across twelve locations in four eutrophic lakes and within-lake locations in the Yahara Watershed, WI, on a weekly basis, for 5 months. Taxa were discriminated by length of MspI-digested cpcB/A intergenic spacer gene sequences and identified by comparison to a PCR-based clone library. CCC across all stations was spatially segregated by depth of sampling locations (ANOSIM R = 0.23, p < 0.001). Accordingly, CCC was correlated with thermal stratification, nitrate and soluble reactive phosphorus (SRP, R = 0.2-0.3). Spatial variability in CCC and temporal trends in taxa abundances were rarely correlative between sampling locations in the same lake indicating significant within lake spatiotemporal heterogeneity. Across all stations, a total of 37 bloom events were observed based on distinct increases in phycocyanin. Out of 97 taxa, a single Microcystis, and two different Aphanizomenon taxa were the dominant cyanobacteria detected during bloom events. The Microcystis and Aphanizomenon taxa rarely bloomed together and were significantly anti-correlated with each other at 9 of 12 stations with Pearson R values of -0.6 to -0.9 (p < 0.001). Of all environmental variables measured, nutrients, especially nitrate were significantly greater during periods of Aphanizomenon dominance while the nitrate+nitrite:SRP ratio was lower. This study shows significant spatial variability in CCC within and between lakes structured by depth of the sampling location. Furthermore, our study reveals specific genotypes involved in bloom formation. More in-depth characterization of these genotypes should lead to a better understanding of factors promoting bloom events in these lakes and more reliable bloom prediction models.
Occurrence of toxin-producing cyanobacteria blooms in a Brazilian semiarid reservoir
Costa, I. A. S.;Azevedo, S. M. F. O;Senna, P. A. C.;Bernardo, R. R.;Costa, S. M.;Chellappa, N. T.;
Brazilian Journal of Biology , 2006, DOI: 10.1590/S1519-69842006000200005
Abstract: we report the occurrence of cyanobacterial blooms and the presence of cyanotoxins in water samples from the armando ribeiro gon?alves reservoir (06° 08? s and 37° 07? w), located in the state of rio grande do norte, in the semiarid region of northeastern brazil. the cyanobacterial species were identified and quantified during the rainy and dry seasons in the year 2000. cyanotoxins such as microcystins, saxitoxins and cylindrospermopsins were analyzed and quantified using hplc and elisa methods. the mixed toxic blooms of cylindrospermopsis raciborskii, microcystis spp (m. panniformis, m. protocystis, m. novacekii) and aphanizomenon spp (aphanizomenon gracile, a. cf. manguinii, a. cf. issastschenkoi) were persistent and represented 90-100% of the total phytoplankton species. toxic cyanobacterial blooms from the armando ribeiro gon?alves reservoir were analyzed and found to have three phases in relation to the annual cycle. during the rainy season, an intense toxic bloom of cylindrospermopsis raciborskii was recorded along with saxitoxins (3.14 μg.l-1). during the transition period, between the rainy and dry seasons, different species of microscytis occurred and microcystin as high as 8.8 μg.l-1 was recorded. in the dry season, co-dominance of cylindrospermopsis raciborskii, microcystis spp and aphanizomenon spp occurred and the concentrations of saxitoxin remained very low. our results indicate the presence of microcystins (8.8 μg.l-1) and saxitoxins (3.14 μg.l-1) into the crude water, with increasing concentrations from the second fortnight of april to late may 2000. the occurrence of toxic blooms in this reservoir points to a permanent risk of cyanotoxins in supply waters, indicating the need for the implementation of bloom control measures to improve the water quality. exposure of the local population to cyanotoxins through their potential accumulation in fish muscle must also be considered.
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