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  • 1
    Publication Date: 2021-05-19
    Description: Morphological and genetic diversity of cultured cynobacterial strains of species of the genera Arthrospira, Spirulina and Phormidium from two geographically different regions and habitats (Kenyan saline-alkaline lakes and Indian freshwater bodies) were investigated. Light microscopy observations were used to determine morphological diversity of the cyanobacteria. Three independent molecular techniques, sequencing of 16S rRNA gene, internally transcribed spacer region between 16S and 23S rDNA (ITS) and the phycocyanin locus (PC-IGS) were conducted for the examination of phylogenetic relationship. Despite differences in morphology and habitats the Kenyan and Indian Arthrospira strains belong to the same cluster in phylogenetic trees of the 16S rDNA (AY575923-AY575932) or PC-IGS (AY575937-AY575946). The DNA similarity in both methods was 100%. In the ITS tree, the two Indian Arthrospira strains PD1998/pus (AY575930) and PD2002/ana (AY575932) form their own sub-cluster. The Phormidium strain AB2002/07 (AY575933) from Lake Nakuru, Kenya is included in the Arthrospira cluster in the ITS tree and very closely related in the 16S and PC-IGS trees. Based on 16S rDNA and PC-IGS phylogeny the sequences of the Spirulina strains form a separate cluster distinct from the Arthrospira cluster. The Kenyan and Indian Spirulina subsalsa strains show a considerable genetic variability as similarities in 16S rRNA gene sequence is 91.5% only. Molecular characterizations of cyanobacterial strains in the present study demonstrate that several distinct morphotypes may be genetically similar and vice versa.
    Description: Published
    Keywords: Phylogenetics ; Organism morphology ; Bacteria ; Freshwater organisms ; DNA
    Repository Name: AquaDocs
    Type: Report Section , Not Known
    Format: pp.127-147
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  • 2
    Publication Date: 2021-05-19
    Description: For decades frequent mass mortalities of Lesser Flamingos (Phoeniconaias minor Geoffroy) have been observed at alkaline-saline Kenyan Rift Valley lakes. To estimate the potential influence of toxic cyanobacteria on these mass deaths, the phytoplankton communities were investigated in Lakes Bogoria, Nakuru, and Elmenteita. Cyanobacterial toxins were analyzed both in the phytoplankton from the three lakes and in isolated monocyanobacterial strains of Arthrospira fusiformis, Anabaenopsis abijatae, Spirulina subsalsa and Phormidium terebriformis. Lake Bogoria was dominated by the cyanobacterium A. fusiformis. In L. Nakuru and L. Elmenteita the phytoplankton mainly consisted of A. fusiformis, Anabaenopsis abijatae and A. arnoldii, and in L. Nakuru an unknown Anabaena sp. was also found. Furthermore, this is the first time A. abijatae and the unknown Anabaena sp. have been found in Kenyan lakes. Phytoplankton wet weight biomass was found to be high, reaching 777 mg L-1 in L. Bogoria, 104 mg L-1 in L. Nakuru and 202 mg L-1 in L. Elmenteita. Using HPLC, the cyanobacterial hepatotoxins microcystin-LR, -RR -YR, -LF and -LA and the neurotoxin anatoxin-a were detected in phytoplankton samples from L. Bogoria and L. Nakuru. Total microcystin concentrations amounted to 155 μg microcystin-LR equivalents g-1 DW in L. Bogoria, and 4593 μg microcystin-LR equivalents g-1 DW in L. Nakuru, with anatoxin-a concentrations at 9 μg g-1 DW in L. Bogoria and 223 μg g-1 DW in L. Nakuru. In L. Elmenteita phytoplankton, no cyanobacterial toxins were found. A. fusiformis was identified as one source of the toxins. The isolated strain of A. fusiformis from L Bogoria was found to produce both microcystin-YR (15.0 μg g-1 DW) and anatoxin-a (10.4 μg g-1 DW), whilst the A. fusiformis strain from L. Nakuru was found to produce anatoxin-a (0.14 μg g-1 DW). Since A. fusiformis mass developments are characteristic of alkaline-saline lakes, health risks to wildlife, especially the Arthrospira-consuming Lesser Flamingo, may be expected.
    Description: Published
    Keywords: Bacteria ; Phytoplankton ; Biological poisons ; Toxicology ; Alkalinity ; Chemical properties ; Freshwater lakes
    Repository Name: AquaDocs
    Type: Report Section , Not Known
    Format: pp.83-105
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  • 3
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    Freie Universität Berlin | Berlin, Germany
    Publication Date: 2021-05-19
    Description: The phytoplankton communities and the production of cyanobacterial toxins were investigated in two alkaline Kenyan crater lakes, Lake Sonachi and Lake Simbi. Lake Sonachi was mainly dominated by the cyanobacterium Arthrospira fusiformis, Lake Simbi by Arthrospira fusiformis and Anabaenopsis abijatae. The phytoplankton biomasses measured were high, reaching up to 3159 mg l-1 in L. Sonachi and up to 348 mg l-1 in L. Simbi. Using HPLC techniques, in L. Sonachi one structural variant of the hepatotoxin microcystin (microcystin-RR) was found in L. Sonachi and four variants (microcystin- LR, -RR, -LA and -YR) were identified in L. Simbi. The neurotoxin anatoxin-a was found in both lakes. To our knowledge this is the first evidence of cyanobacterial toxins in L. Sonachi and L. Simbi. Total microcystin concentrations varied from 1.6 to 12.0 μg microcystin-LR equivalents g-1 DW in L. Sonachi and from 19.7 to 39.0 μg microcystin-LR equivalents g-1 DW in L. Simbi. Anatoxin-a concentrations ranged from 0.5 to 2.0 μg g-1 DW in L. Sonachi and from 0 to 1.4 μg g-1 DW in L. Simbi. In a monocyanobacterial strain of Arthrospira fusiformis, isolated from L. Sonachi, microcystin-YR and anatoxin-a were produced. The concentrations found were 2.2 μg microcystin g-1 DW and 0.3 μg anatoxin-a g-1 DW. This is the first study showing Arthrospira fusiformis as producer of microcystins and anatoxin-a. Since Arthrospira fusiformis occurs in mass developments in both lakes, a health risk for wildlife can be expected.
    Description: Unpublished
    Keywords: Bacteria ; Phytoplankton ; Biological poisons ; Toxicology ; Inland waters ; Freshwater lakes ; Poisonous organisms
    Repository Name: AquaDocs
    Type: Report Section , Not Known
    Format: pp.106-126
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  • 4
    Publication Date: 2022-05-27
    Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Gosselin, K. M., Nelson, R. K., Spivak, A. C., Sylva, S. P., Van Mooy, B. A. S., Aeppli, C., Sharpless, C. M., O’Neil, G. W., Arrington, E. C., Reddy, C. M., & Valentine, D. L. Production of two highly abundant 2-methyl-branched fatty acids by blooms of the globally significant marine cyanobacteria Trichodesmium erythraeum. ACS Omega, 6(35), (2021): 22803–22810, https://doi.org/10.1021/acsomega.1c03196.
    Description: The bloom-forming cyanobacteria Trichodesmium contribute up to 30% to the total fixed nitrogen in the global oceans and thereby drive substantial productivity. On an expedition in the Gulf of Mexico, we observed and sampled surface slicks, some of which included dense blooms of Trichodesmium erythraeum. These bloom samples contained abundant and atypical free fatty acids, identified here as 2-methyldecanoic acid and 2-methyldodecanoic acid. The high abundance and unusual branching pattern of these compounds suggest that they may play a specific role in this globally important organism.
    Description: This work was funded with grants from the National Science Foundation grants OCE-1333148, OCE-1333162, and OCE-1756254 and the Woods Hole Oceanographic Institution (IR&D). GCxGC analysis made possible by WHOI’s Investment in Science Fund.
    Keywords: Lipids ; Alkyls ; Bacteria ; Genetics ; Chromatography
    Repository Name: Woods Hole Open Access Server
    Type: Article
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