scholarly journals Microcystin Biosynthesis andmcyAExpression in Geographically DistinctMicrocystisStrains under Different Nitrogen, Phosphorus, and Boron Regimes

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Ankita Srivastava ◽  
So-Ra Ko ◽  
Chi-Yong Ahn ◽  
Hee-Mock Oh ◽  
Alok Kumar Ravi ◽  
...  
Keyword(s):  
South Korea ◽  
Environmental Variables ◽  
Reference Strain ◽  
Heterotrophic Bacteria ◽  
Cyanobacterial Bloom ◽  
Photoautotrophic Growth ◽  
Microcystin Concentration ◽  
Alpha Beta ◽  
Nitrogen Phosphorus

Roles of nutrients and other environmental variables in development of cyanobacterial bloom and its toxicity are complex and not well understood. We have monitored the photoautotrophic growth, total microcystin concentration, and microcystins synthetase gene (mcyA) expression in lab-grown strains ofMicrocystisNIES 843 (reference strain), KW (Wangsong Reservoir, South Korea), and Durgakund (Varanasi, India) under different nutrient regimes (nitrogen, phosphorus, and boron). Higher level of nitrogen and boron resulted in increased growth (avg. 5 and 6.5 Chlamg/L, resp.), total microcystin concentrations (avg. 1.185 and 7.153 mg/L, resp.), andmcyAtranscript but its expression was not directly correlated with total microcystin concentrations in the target strains. Interestingly, Durgakund strain had much lower microcystin content and lacked microcystin-YR variant over NIES 843 and KW. It is inferred that microcystin concentration and its variants are strain specific. We have also examined the heterotrophic bacteria associated with cyanobacterial bloom in Durgakund Pond and Wangsong Reservoir which were found to be enriched in Alpha-, Beta-, and Gammaproteobacteria and that could influence the bloom dynamics.

scholarly journals Distribution Patterns of Odonate Assemblages in Relation to Environmental Variables in Streams of South Korea

Insects ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 152 ◽  
Author(s):  
Da-Yeong Lee ◽  
Dae-Seong Lee ◽  
Mi-Jung Bae ◽  
Soon-Jin Hwang ◽  
Seong-Yu Noh ◽  
...  
Keyword(s):  
Land Use ◽  
Ecosystem Services ◽  
Environmental Factors ◽  
South Korea ◽  
Habitat Heterogeneity ◽  
Environmental Variables ◽  
Environmental Changes ◽  
Distribution Patterns ◽  
Self Organizing Map ◽  
Factors Affecting

Odonata species are sensitive to environmental changes, particularly those caused by humans, and provide valuable ecosystem services as intermediate predators in food webs. We aimed: (i) to investigate the distribution patterns of Odonata in streams on a nationwide scale across South Korea; (ii) to evaluate the relationships between the distribution patterns of odonates and their environmental conditions; and (iii) to identify indicator species and the most significant environmental factors affecting their distributions. Samples were collected from 965 sampling sites in streams across South Korea. We also measured 34 environmental variables grouped into six categories: geography, meteorology, land use, substrate composition, hydrology, and physicochemistry. A total of 83 taxa belonging to 10 families of Odonata were recorded in the dataset. Among them, eight species displayed high abundances and incidences. Self-organizing map (SOM) classified sampling sites into seven clusters (A–G) which could be divided into two distinct groups (A–C and D–G) according to the similarities of their odonate assemblages. Clusters A–C were characterized by members of the suborder Anisoptera, whereas clusters D–G were characterized by the suborder Zygoptera. Non-metric multidimensional scaling (NMDS) identified forest (%), altitude, and cobble (%) in substrata as the most influential environmental factors determining odonate assemblage compositions. Our results emphasize the importance of habitat heterogeneity by demonstrating its effect on odonate assemblages.

scholarly journals Deciphering the effects of nitrogen, phosphorus, and temperature on cyanobacterial bloom intensification, diversity, and toxicity in western Lake Erie

2019 ◽  
Vol 64 (3) ◽  
pp. 1347-1370 ◽  
Author(s):  
Jennifer Jankowiak ◽  
Theresa Hattenrath‐Lehmann ◽  
Benjamin J. Kramer ◽  
Megan Ladds ◽  
Christopher J. Gobler
Keyword(s):  
Lake Erie ◽  
Cyanobacterial Bloom ◽  
Western Lake ◽  
Nitrogen Phosphorus ◽  
Western Lake Erie

scholarly journals UNICELLULAR PLANKTON TRANSFORMATION IN THE RIVER-BAY-RESERVOIR SYSTEM IN THE INITIAL PHASE OF CYANOBACTERIAL BLOOM

2021 ◽  
Vol 23 (5) ◽  
pp. 144-151
Author(s):  
M.V. Umanskaya ◽  
◽  
S.V. Bykova ◽  
M.Yu. Gorbunov ◽  
E.S. Krasnova ◽  
...  
Keyword(s):  
Structural Transformation ◽  
Initial Phase ◽  
Heterotrophic Bacteria ◽  
Initial Period ◽  
Cyanobacterial Bloom ◽  
Kuibyshev Reservoir ◽  
Adjacent Section ◽  
Reservoir System ◽  
Plankton Biomass ◽  
Quantitative Characteristics

The structure and spatial distributionof unicellular plankton of the river Usa, Usinsky Bay and the adjacent section of the Kuibyshev reservoir in the initial period of cyanobacterial bloom is discussed. The greatest development of plankton was recorded in the central part of Usinsky Bay. In the river part, the basis of the total plankton biomass was formed by heterotrophic bacteria and diatoms, and in the bay and reservoir –by cyanobacteria, mainly of the genera Aphanizomenon and Anabaena. Among eukaryotes in Usinskiy Bay, chlorophytesand diatoms prevailed, and in the reservoir - diatoms and ciliates. Another feature of plankton in the bay and reservoir was the increased proportion of heterotrophic bacteria and ciliates associated with cyanobacteria. The analysis of the structural transformation of communities made it possible to distinguish two main clusters of communities, "lotic" and "letic", which differ in their structure and quantitative characteristics.

Summer changes in cyanobacterial bloom composition and microcystin concentration in eutrophic Czech reservoirs

2006 ◽  
Vol 21 (3) ◽  
pp. 236-243 ◽  
Author(s):  
Petr Znachor ◽  
Tomasz Jurczak ◽  
Jaroslava Komárková ◽  
Jitka Jezberová ◽  
Joanna Mankiewicz ◽  
...  
Keyword(s):  
Cyanobacterial Bloom ◽  
Microcystin Concentration

scholarly journals Status, Alert System, and Prediction of Cyanobacterial Bloom in South Korea

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Ankita Srivastava ◽  
Chi-Yong Ahn ◽  
Ravi Kumar Asthana ◽  
Hyung-Gwan Lee ◽  
Hee-Mock Oh
Keyword(s):  
South Korea ◽  
Prediction Models ◽  
Current Knowledge ◽  
Management Strategies ◽  
Cyanobacterial Bloom ◽  
Field Studies ◽  
Toxin Production ◽  
Ecological Problem ◽  
South Korean ◽  
Freshwater Bodies

Bloom-forming freshwater cyanobacterial genera pose a major ecological problem due to their ability to produce toxins and other bioactive compounds, which can have important implications in illnesses of humans and livestock. Cyanobacteria such asMicrocystis, Anabaena, Oscillatoria, Phormidium, andAphanizomenonspecies producing microcystins and anatoxin-a have been predominantly documented from most South Korean lakes and reservoirs. With the increase in frequency of such blooms, various monitoring approaches, treatment processes, and prediction models have been developed in due course. In this paper we review the field studies and current knowledge on toxin producing cyanobacterial species and ecological variables that regulate toxin production and bloom formation in major rivers (Han, Geum, Nakdong, and Yeongsan) and reservoirs in South Korea. In addition, development of new, fast, and high-throughput techniques for effective monitoring is also discussed with cyanobacterial bloom advisory practices, current management strategies, and their implications in South Korean freshwater bodies.

scholarly journals Distinctive tasks of different cyanobacteria and associated bacteria in carbon as well as nitrogen fixation and cycling in a late stage Baltic Sea bloom

2019 ◽  
Author(s):  
Falk Eigemann ◽  
Angela Vogts ◽  
Maren Voss ◽  
Luca Zoccarato ◽  
Heide Schulz-Vogt
Keyword(s):  
Nitrogen Fixation ◽  
Baltic Sea ◽  
Late Stage ◽  
Carbon Fixation ◽  
Heterotrophic Bacteria ◽  
Cyanobacterial Bloom ◽  
Cyanobacterial Blooms ◽  
Carbon And Nitrogen ◽  
Cyanobacterial Species ◽  
Uptake Rates

AbstractCyanobacteria and associated heterotrophic bacteria hold key roles in carbon as well as nitrogen fixation and cycling in the Baltic Sea due to massive cyanobacterial blooms each summer. The species specific activities of different cyanobacterial species as well as the N- and C-exchange of associated heterotrophic bacteria in these processes, however, are widely unknown. Within one time series experiment we tested the cycling in a natural, late stage cyanobacterial bloom by adding 13C bi-carbonate and 15N2, and performed sampling after 10 min, 30 min, 1 h, 6 h and 24 h in order to determine the fixing species as well as the fate of the fixed carbon and nitrogen in the associations. Uptake of 15N and 13C isotopes by the most abundant cyanobacterial species as well as the most abundant associated heterotrophic bacterial groups was then analysed with a NanoSIMS. Overall, the filamentous, heterocystous species Dolichospermum sp., Nodularia sp., and Aphanizomenon sp. revealed no or erratic uptake of carbon and nitrogen, indicating mostly inactive cells. In contrary, non-heterocystous Pseudanabaena sp. dominated the nitrogen and carbon fixation, with uptake rates up to 1.49 ± 0.47 nmol N h-1 l-1 and 2.55 ± 0.91 nmol C h-1 l-1. Associated heterotrophic bacteria dominated the subsequent nitrogen cycling with uptake rates up to 1.2 ± 1.93 fmol N h-1 cell -1, but were also indicative for fixation of di-nitrogen.

scholarly journals Influence of Cyanobacterial Bloom on Freshwater Biocoenosis. Use of Bioassays for Cyanobacterial Microcystins Toxicity Assessment

2017 ◽  
Vol 24 (1) ◽  
pp. 47-68 ◽  
Author(s):  
Marlena Piontek ◽  
Wanda Czyżewska
Keyword(s):  
Escherichia Coli ◽  
Daphnia Magna ◽  
Enterococcus Faecalis ◽  
Aquatic Invertebrates ◽  
Methanol Extract ◽  
Heterotrophic Bacteria ◽  
Cyanobacterial Bloom ◽  
Toxicity Assessment ◽  
Cyanobacterial Blooms ◽  
Dugesia Tigrina

Abstract The issues presented in this study concern a very important problem of the occurrence of cyanobacterial blooms in surface water used for water supply purposes. The objective of this study was to analyze the occurrence of cyanotoxic risk in the catchment area of the Obrzyca River (including Sławskie lake which is the beginning of the river), which is a source of drinking water for the inhabitants of Zielona Góra. In order to evaluate toxicity of cyanobacterial bloom it was conducted toxicological testing using aquatic invertebrates (Daphnia magna, Dugesia tigrina) and heterotrophic bacteria (Escherichia coli, Enterococcus faecalis, Pseudomonas fluorescens). Test samples were collected from May to October, 2012. The most toxic was a sample collected from Lake Sławskie on 20th October when cyanobacteria bloom with a predominance of Microcystis aeruginosa occurred and the amount of microcystins was the largest. The methanol extract of the sample was toxic only above a concentration of 6·103 mg·dm-3. The lethal concentration (48-h LC 50) for Daphnia magna was 3.09·103 and for Dugesia tigrina (240-h LC 50) 1.51·103 mg·dm-3 of microcystins (MC-LR, MC-YR and MC-RR). The same extract stimulated growth of Escherichia coli and Enterococcus faecalis cells.

scholarly journals Interkingdom Cross-Feeding of Ammonium from Marine Methylamine-Degrading Bacteria to the Diatom Phaeodactylum tricornutum

2016 ◽  
Vol 82 (24) ◽  
pp. 7113-7122 ◽  
Author(s):  
Marcel Suleiman ◽  
Karsten Zecher ◽  
Onur Yücel ◽  
Nina Jagmann ◽  
Bodo Philipp
Keyword(s):  
Nitrogen Source ◽  
Phaeodactylum Tricornutum ◽  
Heterotrophic Bacteria ◽  
Phytoplankton Growth ◽  
Marine Phytoplankton ◽  
Methylotrophic Bacteria ◽  
Photoautotrophic Growth ◽  
Content Type ◽  
Degrading Bacteria ◽  
Proof Of Principle

ABSTRACTMethylamines occur ubiquitously in the oceans and can serve as carbon, nitrogen, and energy sources for heterotrophic bacteria from different phylogenetic groups within the marine bacterioplankton. Diatoms, which constitute a large part of the marine phytoplankton, are believed to be incapable of using methylamines as a nitrogen source. As diatoms are typically associated with heterotrophic bacteria, the hypothesis came up that methylotrophic bacteria may provide ammonium to diatoms by degradation of methylamines. This hypothesis was investigated with the diatomPhaeodactylum tricornutumand monomethylamine (MMA) as the substrate. Bacteria supporting photoautotrophic growth ofP. tricornutumwith MMA as the sole nitrogen source could readily be isolated from seawater. Two strains,Donghicolasp. strain KarMa, which harbored genes for both monomethylamine dehydrogenase and theNmethylglutamate pathway, andMethylophagasp. strain M1, which catalyzed MMA oxidation by MMA dehydrogenase, were selected for further characterization. While strain M1 grew with MMA as the sole substrate, strain KarMa could utilize MMA as a nitrogen source only when, e.g., glucose was provided as a carbon source. With both strains, release of ammonium was detected during MMA utilization. In coculture withP. tricornutum, strain KarMa supported photoautotrophic growth with 2 mM MMA to the same extent as with the equimolar amount of NH4Cl. In coculture with strain M1, photoautotrophic growth ofP. tricornutumwas also supported, but to a much lower degree than by strain KarMa. This proof-of-principle study with a synthetic microbial community suggests that interkingdom cross-feeding of ammonium from methylamine-degrading bacteria is a contribution to phytoplankton growth which has been overlooked so far.IMPORTANCEInteractions between diatoms and heterotrophic bacteria are important for marine carbon cycling. In this study, a novel interaction is described. Bacteria able to degrade monomethylamine, which is a ubiquitous organic nitrogen compound in marine environments, can provide ammonium to diatoms. This interkingdom metabolite transfer enables growth under photoautotrophic conditions in coculture, which would not be possible in the respective monocultures. This proof-of-principle study calls attention to a so far overlooked contribution to phytoplankton growth.

Phase Transformations in Ti-7w/oMo-3w/oMe Alloy

1974 ◽  
Vol 32 ◽  
pp. 514-515
Author(s):  
S. Fujishiro
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Mechanical Processing ◽  
Ray Method ◽  
X Ray ◽  
Transmission Electron ◽  
Water Quench ◽  
Alpha Beta

The mechanical properties of three titanium alloys (Ti-7Mo-3Al, Ti-7Mo- 3Cu and Ti-7Mo-3Ta) were evaluated as function of: 1) Solutionizing in the beta field and aging, 2) Thermal Mechanical Processing in the beta field and aging, 3) Solutionizing in the alpha + beta field and aging. The samples were isothermally aged in the temperature range 300° to 700*C for 4 to 24 hours, followed by a water quench. Transmission electron microscopy and X-ray method were used to identify the phase formed. All three alloys solutionized at 1050°C (beta field) transformed to martensitic alpha (alpha prime) upon being water quenched. Despite this heavily strained alpha prime, which is characterized by microtwins the tensile strength of the as-quenched alloys is relatively low and the elongation is as high as 30%.

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