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Growth and Toxin Production by Microcystis Aeruginosa PCC 7806 (Kutzing) Lemmerman at Elevated Salt Concentrations  [PDF]
Ken Black, Mete Yilmaz, Edward J. Phlips
Journal of Environmental Protection (JEP) , 2011, DOI: 10.4236/jep.2011.26077
Abstract: One of the most common and widespread bloom-forming cyanobacteria associated with toxin production is Microcystis aeruginosa (Kutzing) Lemmerman. While normally associated with fresh water environments, this toxigenic species has been observed at bloom concentrations in a number of major estuaries worldwide. This study examined the effect of salinity on growth and toxin production by M. aeruginosa strain PCC 7806 under controlled laboratory conditions. Salt concentrations above 12.6 ppt resulted in total cessation of growth. Toxin production was similarly affected, with cultures grown in salt concentrations of 4.6 ppt and above yielding less toxin than the control after 20 days of culture. Toxin concentrations after 20 days of culture were 40% of the control at 4.6 ppt. The relative proportion of extracellular to intracellular toxin increased over time in cultures with salt concentrations greater than 4.6 ppt. Extracellular toxins persisted in the media long after the cessation of growth. The results suggest that the influence of M. aeruginosa and/or its toxins can extend well out into estuarine environments under the influence of significant freshwater inputs.
New Records of Microcystins in Some Bulgarian Water Bodies of Health and Conservational Importance  [PDF]
Vera Pavlova, Maya Stoyneva, Vesela Georgieva, Desislav Donchev, Lisa Spoof, Jussi Meriluoto, Zlatka Bratanova, Irina Karadjova
Journal of Water Resource and Protection (JWARP) , 2014, DOI: 10.4236/jwarp.2014.65044
Abstract:

Microcystins cause acute hepatotoxicity and chronic liver tumor promotion. This study presents the results of HPLC DAD analyses and their LC-MS confirmation of samples from five Bulgarian water bodies (reservoirs Stoudena, Pchelina, Bistritsa and lakes Dourankoulak, Vaya). The total concentration of microcystins in water samples ranged from 0.1 to 26.5 μg/l. The amount of microcystins in the biomasses ranged from 11.4 to 49.6 μg/g (d.w.). The high percent of positive samples in which the most toxic microcystin-LR is recorded, can serve as a strong alarm for the necessity of a serious study and relevant discussion of the problem with responsible authorities at national level.

Microcystins-LR, -YR and -RR in Six Bulgarian Water Bodies of Health and Conservational Importance (2012-2014)  [PDF]
Vera Pavlova, Maya Stoyneva-G?rtner, Blagoy Uzunov, Blagoy Uzunov, Zlatka Bratanova, Antoaneta Lazarova, Irina Karadjova
Journal of Water Resource and Protection (JWARP) , 2015, DOI: 10.4236/jwarp.2015.716111
Abstract: This study presented the results of HPLC-DAD microcystin and nodularin analyses from five Bulgarian water bodies (reservoirs Stoudena, Pchelina and Bistritsa, and lakes Dourankoulak and Vaya) carried out in 2012-2014, as a continuation of our work from 2004 to 2005 and in 2011, and first data on microcystins in the lake Momin Brod were detected in the period 2012-2014. The total concentration of microcystins in water samples ranged from 0.1 to 1.8 μg/l and their amount in the concentrated biomasses from net samples ranged from 1.35 to 296 μg/g (d.w.). The presence of the most toxic microcystin-LR was recorded in all studied lakes and reservoirs, where also microcystins RR and YR were detected, but no microcystin-LA and nodularin were found.
Comparative Study on Heavy Metals Biosorption by Different Types of Bacteria  [PDF]
Eteri Gelagutashvili
Open Journal of Metal (OJMetal) , 2013, DOI: 10.4236/ojmetal.2013.32a1008
Abstract: Biosorption of Cd(II), Ag(I) and Au(III) by cyanobacteria Spirulina platensis, of Au(II)—by Streptomyces spp. 19H, and of Cr(VI) and Cr(III)—by Arthrobacter species was studied by using the dialysis and atomic absorption analysis under various conditions. In particular, the impact of the following parameters on biosorption was studied: pH (for Ag, Cd, Au), living and non-living cells (for Cr), heavy metal valence (for Cr), homogenized and non-homogenized cells (for Au), Zn(II) ions (on Cr(VI)—Arthrobacter species). It was shown that biosorption efficiency of Cr(III), Cr(VI), Cd(II), Au(III) and Ag(I) ions is likely to depend on the type of bacteria used as well as on the conditions under which the uptake processes proceeded. It was shown that metal removal by microorganisms was influenced by physical-chemical parameters. The pH value of 7.0 was optimum for the removal of Ag(I) and Cd(II) by Spirulina platensis. At a low pH value of 5.5, Au (III) was by test algae more efficiently than Cd(II) and Ag(I).
Comparative Study on Heavy Metals Biosorption by Different Types of Bacteria  [PDF]
Eteri Gelagutashvili
Open Journal of Metal (OJMetal) , 2013, DOI: 10.4236/ojmetal.2013.32A1008
Abstract: Biosorption of Cd(II), Ag(I) and Au(III) by cyanobacteria Spirulina platensis, of Au(II)—by Streptomyces spp. 19H, and of Cr(VI) and Cr(III)—by Arthrobacter species was studied by using the dialysis and atomic absorption analysis under various conditions. In particular, the impact of the following parameters on biosorption was studied: pH (for Ag, Cd, Au), living and non-living cells (for Cr), heavy metal valence (for Cr), homogenized and non-homogenized cells (for Au), Zn(II) ions (on Cr(VI)—Arthrobacter species). It was shown that biosorption efficiency of Cr(III), Cr(VI), Cd(II), Au(III) and Ag(I) ions is likely to depend on the type of bacteria used as well as on the conditions under which the uptake processes proceeded. It was shown that metal removal by microorganisms was influenced by physical-chemical parameters. The pH value of 7.0 was optimum for the removal of Ag(I) and Cd(II) by Spirulina platensis. At a low pH value of 5.5, Au (III) was by test algae more efficiently than Cd(II) and Ag(I).

Nitrogen Constrains the Growth of Late Summer Cyanobacterial Blooms in Lake Erie  [PDF]
Justin D. Chaffin, Thomas B. Bridgeman, Darren L. Bade
Advances in Microbiology (AiM) , 2013, DOI: 10.4236/aim.2013.36A003
Abstract: Phosphorus (P) is generally considered to be the main limiting nutrient to freshwater phytoplankton productivity. However, recent research is drawing attention to the importance of nitrogen (N) in freshwater eutrophication and N often constrains growth of cyanobacteria in small lakes. In this study we determined phytoplankton nutrient limitation in a large lake, Lake Erie during two growing seasons. During 2010 and 2011, nutrient enrichment bioassays (+P, +N and, +P and N) were conducted monthly from June through September with water collected in Maumee Bay (site MB18) and in the center of the western basin (site WBC). Nutrient concentrations were monitored every other week. At MB18, total P concentration was often >3 mmol/L and nitrate concentration decreased from >250 mmol/L in early summer to <1 mmol/L in late summer. Nitrogen and P levels were about five-fold less at WBC. Bioassays indicated that phytoplankton nutrient limitation varied in summer, spatially, and even among phytoplankton groups. For site MB18, +P increased chlorophyll concentration in one of the eight bioassays, indicating that P did not typically limit production. For site WBC, +P increased chlorophyll concentration in six of the eight bioassays. As a result of very low ambient nitrate concentration (<5 mmol/L) in late summer, +N (without P) increased chlorophyll concentration, suggesting symptoms of N-limitation. The N-fixing cyanobacterium Anabaena became dominant following N-limitation. This study highlights the need to reduce P loading to restore water quality. Furthermore, due to low nitrate concentration, the severity of the cyanobacterial blooms could be worse if not for N-limitation in western Lake Erie.
Isolation and Characterization of Cyanobacterial Community Including a Microcystin-Producing Nostoc sp. Strain in the Nile River, Egypt  [PDF]
Ranya Amer, Rehab Shehawy, Saraa Saad El-Dien, Marwa Abu Serie, Kamel Shaker
Advances in Microbiology (AiM) , 2013, DOI: 10.4236/aim.2013.36A005
Abstract: The combined use of morphological identification and phylogenetic characterization employing primers that target the 16S rDNA region led to the identification of ten isolates belonging to eight cyanobacterial genera in the Nile River. 16S-23S ITS region was amplified to confirm two isolates to be affiliated to genus Nostoc. Using MALDI-TOF/MS, we detected the production of the hepatotoxic demethylated MC-LR by one isolate that clustered together with the genus Nostoc. Protein phosphatase inhibition assay has confirmed toxicity. Our results add to the rising importance of Nostoc as a hepatotoxin-producing cyanobacterium. Furthermore, our results stress that water municipalities in the studied region need to assess the potential threat of toxic cyanobacteria that may pose to human health and economy.
Cyanobacteria Diversity in Blooms from the Greater Sudbury Area  [PDF]
Suzanne Evans, Mazen Saleh
Journal of Water Resource and Protection (JWARP) , 2015, DOI: 10.4236/jwarp.2015.711071
Abstract: The Greater Sudbury Area is approximately 400 km north of the city of Toronto and falls within a large number of temperate lakes of various sizes. This area has been mined for nickel and other metals for several decades. These activities have affected the watersheds of Northern Ontario and have influenced the chemistry of a number of lakes. Blooms of cyanobacteria occur yearly in several lakes, mainly in the early and late summer months. Much of the chemistry of these lakes is known but the nature of the cyanobacterial blooms and the factors that may contribute to their sudden appearance are not. We sampled blooms from five Greater Sudbury Area lakes and identified the species present by morphological and molecular methods. The dominant genera present as characterized by morphological examination were Synechocystis, Leptolyngbya, Anabaena, Cyl-indrospermum, Nostoc, Borzia, Phormidium, Pseudoanabaena, Oscillatoria, and Planktothrix. Three of these isolates, Leptolyngbya, Anabaena, and Planktothrix were confirmed by partial rRNA sequence analysis.
Evaluation of the toxicity of Streptomyces aburaviensis (R9) extract towards various agricultural pests  [PDF]
Ismail Saadoun, Sereen Bataineh, Qutaiba Ababneh, Khalid Hameed, Kevin Schrader, Charles Cantrell, Franck Dayan, David Wedge
Agricultural Sciences (AS) , 2011, DOI: 10.4236/as.2011.24063
Abstract: The dichloromethane extract of culture filtrate from Streptomyces aburaviensis R9 was evaluated using various rapid bioassays to determine potential inhibitory effects towards phytopathogenic fungi (Colletotrichum acutatum, C. fragariae, C. gloeosoprioids, Botrytis cinerea, Fusarium oxysporum, Phomopsis viticola and P. obscurans), fish bacterial pathogens (Edwardsiella ictaluri and Flavobacterium columnare), a green alga (Selenastrum capricornutum), plant seeds [Bent grass (Agrostis sp.) monocot and lettuce (Lactuca sativa) dicot] and 2-methylisoborneol (MIB)-producing cyanobacteria (Planktothrix perornata and Pseudanabaena sp.). The dichloromethane extract showed selective inhibition against the cyanobacterium P. perornata, with a lowest-complete-inhibition concentration (LCIC) of 10 mg/L and lowest-observed-effect concentration (LOEC) of 10 mg/L while LCIC and LOEC values were 100 mg/L when tested against S. capricornutum. This extract also showed slight meristematic cytogenic necrosis at 200 mg/L towards germinated seeds of both test plants. The compounds were not very toxic towards the channel catfish (Ictalurus punctatus) pathogenic bacteria E. ictaluri and F. columnare. Preliminary evaluation of the extract toward C. acutatum, C. fragariae and C. gloeosoprioids using TLC bioautography revealed moderate activity. However, further evaluation of the extract using a microtiter plate bioassay determined that inhibition was strongest against C. acutatum and C. fragariae, though this inhibitory activity diminished at 72 hours and was moderately less active than the commercial fungicides azoxystrobin and captan when comparing 1 - 100 mg/L levels at 48 hours.
First TaqMan Assay to Identify and Quantify the Cylindrospermopsin-Producing Cyanobacterium Aphanizomenon ovalisporum in Water  [PDF]
Elena Campo, María-ángeles Lezcano, Ramsy Agha, Samuel Cirés, Antonio Quesada, Rehab El-Shehawy
Advances in Microbiology (AiM) , 2013, DOI: 10.4236/aim.2013.35058
Abstract:

Cylindrospermopsin (CYN) is an alkaloid that causes hepatotoxicity, neurotoxicity and general cytotoxicity in vertebrates. It is currently gaining widespread attention after its reported appearance in water bodies around the world. A. ovalisporum is capable of CYN-production and can form toxic blooms when favorable environmental conditions are available. We have developed for the first time a two-step qPCR assay using Taqman probes to detect and quantify potential CYN-producing A. ovalisporum in water samples. The assay was sensitive enough to discriminate between CYN-producing and non-CYN-producing A. ovalisporum in a mixed background, and discriminate between A. ovalisporum and other nostocales as C. raciborskii and A. bergii. The detection limit of the assay falls in the log linear range of 102 and 105 gene copies per reaction and is thus within the sensitivity range of previously published assays for the detection of other toxic cyanobacteria species. Our assay allows for the first time to quickly assess water quality for the presence of potentially CYN-producing A. ovalisporum and can be easily used for the purposes of monitoring water bodies.

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