Diversity of Microcystis aeruginosa isolates (Chroococcales, Cyanobacteria) from East-African water bodies (original) (raw)
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DETECTION OF POTENTIALLY TOXIC MICROCYSTISAND CYANOBACTERIA BY MOLECULAR METHOD IN CÔTE d'IVOIRE
2015
The cyanobacteria or blue-green algae are natural inhabitants of water bodies. The eutrophication due to anthropogenic pressure favors the massive development of strains of cyanobacteria, some of which are potentially toxic. The main goal of this work was to demonstrate for the first time in Ivory Coast the presence of toxicity gene of cyanobacteria from cyanobacteria culture. Water used by the population for their different needed were sampled in different cities of the country. Several genera known for their ability to produce toxic were highlighted including Microcystis, anabeana, oscillatoria, plancktothrix. Oscillatoria was the most isolated genus with 93% of presence in the samples. The pcr has allowed us to confirm the existence of the gene mcy encoding microcystin in Microcystis. PCR identified the mcygène of microcystis in all the sample (100%) while microcystis was found only 86% by microscopy. The contribution of chromatographic and ELISA techniques will ultimately confirm their toxin production or not.
Brazilian Archives of Biology and Technology, 2009
The escalating occurrence of cyanobacterial toxic blooms demands a better understanding of genetic variability as an auxiliary expedient in species identification, collaborating with the monitoring of water destined to public supply. This study aimed at the unraveling of genetic polymorphism in the toxic and nontoxic strains of Microcystis (Cyanobacteria) species, isolated from diverse Brazilian localities through the RFLP-PCR technique applied to the c-phycocyanin encoding operon and its intergenic spacer (cpcBA-IGS). Eighteen strains belonging to M. aeruginosa, M. panniformis, M. protocystis and M. wesenbergii, plus two other unidentified strains, were analyzed by means of the morphological and molecular data. The molecular data constituted three groups with low similarity values unrelated to the geographical origin, toxicity or morphospecies. A high genetic variability among the studied populations was unveiled by the results. Brazilian populations of Microcystis spp. displayed high genetic diversity when compared to those from Australia, Japan, United States and Europe. This ample genetic diversity could be observed through the diverse eletrophoretic profiles obtained among the strains from a single species. The presence of toxic and non-toxic strains was observed in the same species, as M. aeruginosa.
AFRICAN JOURNAL OF BIOTECHNOLOGY, 2011
Mozambique is a developing country with a wide range of aquatic ecosystems. Given the limited resources of the country, problems of aquatic pollution have not received the required consideration. The aim of the present study was to assess the presence of microcystins (MCs) and identify the genotypes of MC-producing cyanobacteria in Mozambique. Polymerase chain reaction (PCR) based detection methods were used to analyze samples from three study freshwater bodies which are used as sources of drinking water. The occurrence of cyanobacterial toxic genes in Nhambavale lake and Chòkwé irrigation channels is reported based on general and genus-specific PCR amplification of the cpcB-cpcA, mcyA and mcyB genes. The genera of MC-producing cyanobacteria were differentiated by restriction fragment length polymorphism (RFLPs) analysis. Microcystis was identified as the predominant potential MC-producing genera. Analysis for MCs in passive sampling devices (PSDs) by liquid chromatography-mass spectroscopy (LC-MS) revealed 3 MC variants (MC-LR,-YR and-RR) at concentrations of 2.1 to 159.4 ng/g of PSD. MC-LR was the dominant variant which was detected in all study sites. This study has established that Microcystis was the predominant genotype and it may be the genus responsible for the production of the MCs detected in water. Results from this study showed that the RFLPs method was able to differentiate MC-producing from the non-MC-producing cyanobacteria in Mozambique.
Occurrence of microcystin-producing cyanobacteria in Ugandan freshwater habitats
Environmental Toxicology, 2009
Microcystins (MCs) are cyclic heptapeptides that are the most abundant toxins produced by cyanobacteria in freshwater. The phytoplankton of many freshwater lakes in Eastern Africa is dominated by cyanobacteria. Less is known, however, on the occurrence of MC producers and the production of MCs. Twelve Ugandan freshwater habitats ranging from mesotrophic to hypertrophic conditions were sampled in May and June of 2004 and April of 2008 and were analyzed for their physico-chemical parameters, phytoplankton composition, and MC concentrations. Among the group of the potential MC-producing cyanobacteria, Anabaena (0 -10 7 cells ml −1 ) and Microcystis (10 3 -10 7 cells ml −1 ) occurred most frequently and dominated in eutrophic systems. A significant linear relationship (n = 31, r 2 = 0.38, p < 0.001) between the Microcystis cell numbers and MC concentration (1.3-93 fg of MC cell −1 ) was observed. Beside [MeAsp 3 , Mdha 7 ]-MC-RR two new microcystins, [Asp 3 ]-MC-RY and [MeAsp 3 ]-MC-RY were isolated and their constitution assigned by LC-MS 2 .
The Science of the total environment, 2012
Water pollution caused by toxic cyanobacteria is a problem worldwide, increasing with eutrophication. Due to its biological significance, genotoxicity should be a focus for biomonitoring pollution owing to the increasing complexity of the toxicological environment in which organisms are exposed. Cyanobacteria produce a large number of bioactive compounds, most of which lack toxicological data. Microcystins comprise a class of potent cyclic heptapeptide toxins produced mainly by Microcystis aeruginosa. Other natural products can also be synthesized by cyanobacteria, such as the protease inhibitor, aeruginosin. The hepatotoxicity of microcystins has been well documented, but information on the genotoxic effects of aeruginosins is relatively scarce. In this study, the genotoxicity and ecotoxicity of methanolic extracts from two strains of M. aeruginosa NPLJ-4, containing high levels of microcystin, and M. aeruginosa NPCD-1, with high levels of aeruginosin, were evaluated. Four endpoints, using plant assays in Allium cepa were applied: rootlet growth inhibition, chromosomal aberrations, mitotic divisions, and micronucleus assays. The microcystin content of M. aeruginosa NPLJ-4 was confirmed through ELISA, while M. aeruginosa NPCD-1 did not produce microcystins. The extracts of M. aeruginosa NPLJ-4 were diluted at 0.01, 0.1, 1 and 10 ppb of microcystins; the same procedure was used to dilute M. aeruginosa NPCD-1 used as a parameter for comparison, and water was used as the control. The results demonstrated that both strains inhibited root growth and induced rootlet abnormalities. The strain rich in aeruginosin was more genotoxic, altering the cell cycle, while microcystins were more mitogenic. These findings indicate the need for future research on non-microcystin producing cyanobacterial strains. Understanding the genotoxicity of M. aeruginosa extracts can help determine a possible link between contamination by aquatic cyanobacteria and high risk of primary liver cancer found in some areas as well as establish water level limits for compounds not yet studied.
First report of microcystins from a Brazilian isolate of the cyanobacteriumMicrocystis aeruginosa
Journal of Applied Phycology, 1994
This is the first report on microcystins, cyclic heptapeptide hepatotoxins, from Brazilian water supplies. A colony isolate (NPJB-l) of the colonial cyanobacterium Microcystis aeruginosa from Lagoa das Gan;as, Sao Paulo, was cultured under non-axenic conditions. Exponential phase cells were harvested, concentrated and lyophilized for mouse bioassays and toxin extraction. The LDlOO oflyophilized cell suspensions was approximately 31 mg kg-1 (dry cell weight/animal weight). Isolation, purification and characterization of the toxins were carried out by reversed phase HPLC, HPLC amino acid analysis and fast atom bombardment mass spectrometry. Strain NPJB 1 produces two different hepatotoxic heptapeptide microcystins. The main one was microcystin-LR, the most commonly reported microcystin from cyanobacteria. The other was microcystin-LF, the phenylalanine variant of microcystin-LR. This is the first published report for microcystin-LF.
Does the potentially toxic cyanobacterium Microcystis exist in the soda lakes of East Africa?
Hydrobiologia, 2011
Presently, the food chains of the famous saline alkaline flamingo-lakes of East Africa are the focus of intense scientific discussion as the lakes host toxic cyanobacteria, which when consumed by Lesser Flamingos, weaken the birds and therefore make them susceptible to attacks by infective diseases. The distribution, genetic and toxicological aspects of Microcystis in Kenya has been studied extensively. Although there are reports on the occurrence of Microcystis in Kenya's hypersaline alkaline lakes, they have not been confirmed. Our investigations carried out over a 10-year period in about 50 inland waters showed that Microcystis occurs exclusively in freshwaters, but never in the hypersaline alkaline lakes. Microscopic examinations of the phytoplankton of these lakes revealed the presence of Anabaenopsis abijatae (Nostococales) whose lumpy structure makes it roughly similar to Microcystis when viewed under an inverted microscope. We conclude that the possible occurrence of Microcystis in hypersaline alkaline lakes is doubtful and, as such, confirmatory studies including microphotographic documentation of findings should be carried out. Keywords Anabaenopsis Á East Africa Á Lesser Flamingo Á Microcystis Á Soda lakes Á Toxic cyanobacteria Members of the bloom-and scum-forming cyanobacterial genus Microcystis are worldwide found in inland waters where they are the main toxin-producers (Codd et al., 2005). The toxins produced by Microcystis are hepatotoxic microcystins. These are cyclic heptapeptides in more than 60 structural variants with the potential to cause considerable ecotoxicological effects (Wiegand & Pflugmacher, 2005). The species concept of Microcystis is still under discussion and to date, no correlation between morphology, phylogeny, and geography has been established (Otsuka et al., 1999; Wilson et al., 2005). Microcystis aeruginosa (Kützing) Kützing, an extremely polymorphic species (Komárek & Anagnostidis, 1998), is the most common and best studied taxon of the genus. In East Africa, Microcystis is widely distributed in fresh and subsaline inland waters (Wood & Talling, 1988; Kebede, 2002; Okello et al., 2010b). M. aeruginosa is genetically (Haande et al., 2007) and toxicologically well studied in the region (Okello et al., 2010a, b). Another common morphospecies of Microcystis in African lakes is Handling editor: Luigi Naselli-Flores
Biokemistri, 2006
Toxic cyanobacteria found in eutrophic, municipal and residential water supplies are an increasing environmental hazard in South Africa. Cyanobacteria produce lethal toxins, and domestic and wild animal deaths are caused by drinking water contaminated by these toxins. Among the species causing death of livestock, blooms of Microcystis aeruginosa are the most common in South Africa. More than 65 microcystins have been isolated to date and they are the most abundant cyanobacterial toxins. Hazards to human health may result from chronic exposure via contaminated water supplies. Microcystins are powerful tumour promoters and inhibitors of protein phosphatase 1 and 2A and they are suspected to be involved in the promotion of primary liver cancer in humans. In this minireview, we discuss the significance of toxic cyanobacteria in South Africa as well as the detection of potential microcystin-producing cyanobacteria strains in South African reservoirs with a mcyB molecular marker. It would be of economic and public health value to be able to detect early stage blooms of cyanobacteria, especially if it is on a sufficiently timely basis for municipalities and recreation facilities to implement a response plan.
Journal of Toxicology and Environmental Health, Part A, 2018
Global proliferation of cyanobacterial blooms associated with climate change and eutrophication constitutes a serious environmental threat. In Hunan Province a freshwater pond located in Changsha City was found to contain high concentrations of cyanobacteria, however, the characteristics of these cyanobacteria at present are not known. This study thus aimed to isolate, identify the most common bloom-forming cyanobacteria in this region and determine the toxigenic characteristics of the predominant cyanobacteria. The cyanobacteria were isolated by serial dilution and identified using polymerase chain reaction (PCR). The cyanotoxins generated by the cyanobacterium were detected using high-performance liquid chromatography with an ultrahigh resolution LTQ Orbitrap Velos Pro ETD mass spectrometry equipped with electrospray ionization interface (HPLC-ESI-MS). One species of cyanobacterium was isolated and identified as Microcystis sp. YFM1 according to the sequence of the 16S ribosome deoxyribonucleic acid (16S rDNA). It was found that this cyanobacterium contained microcystin synthetase B gene (mcyB) and produced three types of cyanotoxins including microcystin-LR, RR and YR. Our findings indicate that the Microcystis sp. YFM1 isolated from the freshwater pond in Hunan Province exhibits unique characteristics distinguishable from other known cyanobacteria.
International Journal of Systematic Bacteriology, 1997
A primary-structure analysis of the 16s rRNA gene was performed with 10 strains representing five described and one unidentified species of the genus Microcystis. The phylogenies determined illustrate the evolutionary affiliations among Microcystis strains, other cyanobacteria, and related plastids and bacteria. A cluster of 10 strains that included hepatotoxic isolates identified as Microcystis aeruginosa formed a monophyletic group. However, the genus Microcystis appeared to be polyphyletic and contained two strains that clustered with unicellular cyanobacteria belonging to the genus Synechococcus. The clustering of related Microcystis strains, including strains involved in the production of the cyclic peptide toxin microcystin, was consistent with cell morphology, gas vacuolation, and the low G+C contents of the genomes. The Microcystis lineage was also distinct from the lineage containing the unicellular genus Synechocystis and the filamentous, heterocystforming genus Nostoc. The secondary structure of a Microcystis 16s rRNA molecule was determined, and genus-specific sequence signatures were used to design primers that permitted identification of the potentially toxic cyanobacteria belonging to the genus Microcystis via DNA amplification.