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Igor S Pessi, Yannick Lara, Benoit Durieu, Pedro de C Maalouf, Elie Verleyen, Annick Wilmotte
The terrestrial Antarctic Realm has recently been divided into 16 Antarctic Conservation Biogeographic Regions (ACBRs) based on environmental properties and the distribution of biota. Despite their prominent role in the primary production and nutrient cycling in Antarctic lakes, cyanobacteria were only poorly represented in the biological dataset used to delineate these ACBRs. Here we provide a first high-throughput sequencing (HTS) insight into the spatial distribution of benthic cyanobacterial communities in Antarctic lakes located in four distinct, geographically distant ACBRs and covering a range of limnological conditions...
March 14, 2018: FEMS Microbiology Ecology
Ciarán L Kelly, George M Taylor, Andrew Hitchcock, Antonio Torres-Méndez, John T Heap
Cyanobacteria are important for fundamental studies of photosynthesis and have great biotechnological potential. In order to better study and fully exploit these organisms, the limited repertoire of genetic tools and parts must be expanded. A small number of inducible promoters have been used in cyanobacteria, allowing dynamic external control of gene expression through the addition of specific inducer molecules. However, the inducible promoters used to date suffer from various drawbacks including toxicity of inducers, leaky expression in the absence of inducer and inducer photolability, the latter being particularly relevant to cyanobacteria which, as photoautotrophs, are grown under light...
March 15, 2018: ACS Synthetic Biology
Maiko K Okajima, Saranyoo Sornkamnerd, Tatsuo Kaneko
Cyanobacteria are regarded as very eco-friendly microreactors for the production of various biomolecules such as polysaccharides by fixing not only carbon but also nitrogen in water. Cyanobacterial polysaccharides having various functional groups such as hydroxyls, carboxyls, sulfates, etc. have the ability to interact with metals or inorganics, to create bionanocomposites. Sacran, a supergiant cyanobacterial anionic polysaccharide extracted from the extracellular matrix of Aphanothece sacrum which is mass-cultivated in freshwater, is mainly used to create functional bionanocomposites...
March 15, 2018: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
Juline M Walter, Fabyano A C Lopes, Mônica Lopes-Ferreira, Lívia M Vidal, Luciana Leomil, Fabiana Melo, Girlene S de Azevedo, Rossandra M S Oliveira, Alba J Medeiros, Adriana S O Melo, Carlos E De Rezende, Amilcar Tanuri, Fabiano L Thompson
Harmful cyanobacterial blooms have become increasingly common in freshwater ecosystems in recent decades, mainly due to eutrophication and climate change. Water becomes unreliable for human consumption. Here, we report a comprehensive study carried out to investigate the water quality of several Campina Grande reservoirs. Our approach included metagenomics, microbial abundance quantification, ELISA test for three cyanotoxins (microcystin, nodularins, and cylindrospermopsin), and in vivo ecotoxicological tests with zebrafish embryos...
2018: Frontiers in Microbiology
Trung Bui, Thanh-Son Dao, Truong-Giang Vo, Miquel Lürling
Warming climate is predicted to promote cyanobacterial blooms but the toxicity of cyanobacteria under global warming is less well studied. We tested the hypothesis that raising temperature may lead to increased growth rates but to decreased microcystin (MC) production in tropical Microcystis strains. To this end, six Microcystis strains were isolated from different water bodies in Southern Vietnam. They were grown in triplicate at 27 °C (low), 31 °C (medium), 35 °C (high) and 37 °C (extreme). Chlorophyll-a-, particle- and MC concentrations as well as dry-weights were determined...
March 14, 2018: Toxins
Vinicius A C Abreu, Rafael V Popin, Danillo O Alvarenga, Patricia D C Schaker, Caroline Hoff-Risseti, Alessandro M Varani, Marli F Fiore
Cylindrospermopsis raciborskii is a freshwater cyanobacterial species with increasing bloom reports worldwide that are likely due to factors related to climate change. In addition to the deleterious effects of blooms on aquatic ecosystems, the majority of ecotypes can synthesize toxic secondary metabolites causing public health issues. To overcome the harmful effects of C. raciborskii blooms, it is important to advance knowledge of diversity, genetic variation, and evolutionary processes within populations...
2018: Frontiers in Microbiology
Jing Qi, Huachun Lan, Ruiping Liu, Huijuan Liu, Jiuhui Qu
The coagulation/flocculation/flotation (C/F/F) process is becoming a popular method for algae-laden water treatment. However, the efficiency of flotation is highly dependent on the ability of the preceding coagulation/flocculation process to form flocculated algae flocs. This study aims to improve the Microcystis aeruginosa flotation efficiency from algae cell and organic matter aspects by applying Fe(II)-regulated pretreatment enhanced Al coagulation process. The ability of the C/F/F process to remove cyanobacterial cells can be enhanced from 8% to 99% at a Fe(II) dose of 30 μM...
March 5, 2018: Water Research
Sean A Newmister, Shasha Li, Marc Garcia-Borràs, Jacob N Sanders, Song Yang, Andrew N Lowell, Fengan Yu, Janet L Smith, Robert M Williams, K N Houk, David H Sherman
Hapalindole alkaloids are a structurally diverse class of cyanobacterial natural products defined by their varied polycyclic ring systems and diverse biological activities. These complex metabolites are generated from a common biosynthetic intermediate by the Stig cyclases in three mechanistic steps: a rare Cope rearrangement, 6-exo-trig cyclization, and electrophilic aromatic substitution. Here we report the structure of HpiC1, a Stig cyclase that catalyzes the formation of 12-epi-hapalindole U in vitro. The 1...
March 12, 2018: Nature Chemical Biology
Fei Zhong, Wei Liu, Mengdan Lv, Zifa Deng, Juan Wu, Hongjiu Ji, Shuiping Cheng
Eutrophication often leads to the periodic proliferation of harmful cyanobacterial blooms (HCBs), which threaten the sustainability of freshwater ecosystems and lead to serious environmental, health and economic damage. Hence, it is vitally important to take effective measures to manage HCBs and associated problems. In this study, vertical flow constructed wetlands (CWs) were operated under different hydraulic loading rates (HLRs) to treat a hyper-eutrophic water body with HCBs. Six sampling ports (representing different layers) were evenly distributed along the water flow direction to study the purification processes of CWs...
March 2018: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Alberto A Esteves-Ferreira, Masami Inaba, Antoine Fort, Wagner L Araújo, Ronan Sulpice
Cyanobacteria are one of the earliest branching groups of organisms on the planet, and during their evolutionary history were submitted to varying selective pressures. Nowadays, cyanobacteria can grow in a variety of conditions, using a large number of nitrogen sources. The control of the nitrogen metabolism in cyanobacteria depends on a fine-tuning regulatory network involving 2-oxoglutarate (2-OG), PII, PipX, and NtcA. This network answers to the cellular 2-OG levels, which reflects the cellular carbon/nitrogen balance, and as an output regulates gene expression, translation, protein activities and thus metabolic pathways...
March 12, 2018: Critical Reviews in Microbiology
Reiko Murakami, Hitomi Hokonohara, Dock-Chil Che, Tomoji Kawai, Takuya Matsumoto, Masahiro Ishiura
The cyanobacterial clock oscillator is composed of three clock proteins: KaiA, KaiB and KaiC. SasA, a KaiC-binding EnvZ-like orthodox histidine kinase involved in the main clock output pathway, exists mainly as a trimer (SasA3mer ) and occasionally as a hexamer (SasA6mer ) in vitro. Previously, the molecular mass of the SasA-KaiCDD complex, where KaiCDD is a mutant KaiC with two Asp substitutions at the two phosphorylation sites, has been estimated by gel-filtration chromatography to be larger than 670 kDa...
March 12, 2018: Genes to Cells: Devoted to Molecular & Cellular Mechanisms
Ewaldo Leitão, Kemal A Ger, Renata Panosso
Top-down grazer control of cyanobacteria is a controversial topic due to conflicting reports of success and failure as well as a bias toward studies in temperate climates with large generalist grazers like Daphnia . In the tropical lowland lakes of Brazil, calanoid copepods of the Notodiaptomus complex dominate zooplankton and co-exist in high abundance with permanent blooms of toxic cyanobacteria, raising questions for grazer effects on bloom dynamics (i.e., top-down control vs. facilitation of cyanobacterial dominance)...
2018: Frontiers in Microbiology
Mizue Asada, Taishi Nishimura, Kentaro Ifuku, Hiroyuki Mino
The binding site of the extrinsic protein PsbP in plant photosystem II was mapped by pulsed electron-electron double resonance, using mutant spinach PsbP (Pro20Cys, Ser82Cys, Ala111Cys, and Ala186Cys) labeled with 4-maleimido-TEMPO (MSL) spin label. The distances between the spin label and the Tyr160 neutral radical (YD ) in PsbD, the D2 subunit of plant photosystem II, were 50.8 ± 3.5 Å, 54.9 ± 4.0 Å, 57.8 ± 4.9 Å, and 58.4 ± 14.1 Å, respectively. The geometry inferred from these distances was fitted to the PsbP crystal structure (PDB: 4RTI) to obtain the coordinates of YD relative to PsbP...
March 7, 2018: Biochimica et Biophysica Acta
Yury B Slonimskiy, Eugene G Maksimov, Evgeny P Lukashev, Marcus Moldenhauer, Cy M Jeffries, Dmitri I Svergun, Thomas Friedrich, Nikolai N Sluchanko
Photosynthesis requires a balance between efficient light harvesting and protection against photodamage. The cyanobacterial photoprotection system uniquely relies on the functioning of the photoactive orange carotenoid protein (OCP) that under intense illumination provides fluorescence quenching of the light-harvesting antenna complexes, phycobilisomes. The recently identified fluorescence recovery protein (FRP) binds to the photoactivated OCP and accelerates its relaxation into the basal form, completing the regulatory circle...
March 7, 2018: Biochimica et Biophysica Acta
N N Sluchanko, Y B Slonimskiy, E G Maksimov
Photoprotective mechanisms of cyanobacteria are characterized by several features associated with the structure of their water-soluble antenna complexes - the phycobilisomes (PBs). During energy transfer from PBs to chlorophyll of photosystem reaction centers, the "energy funnel" principle is realized, which regulates energy flux due to the specialized interaction of the PBs core with a quenching molecule capable of effectively dissipating electron excitation energy into heat. The role of the quencher is performed by ketocarotenoid within the photoactive orange carotenoid protein (OCP), which is also a sensor for light flux...
December 2017: Biochemistry. Biokhimii︠a︡
Christian Beck, Henning Knoop, Ralf Steuer
Cyanobacteria are a monophyletic phylogenetic group of global importance and have received considerable attention as potential host organisms for the renewable synthesis of chemical bulk products from atmospheric CO2. The cyanobacterial phylum exhibits enormous metabolic diversity with respect to morphology, lifestyle and habitat. As yet, however, research has mostly focused on few model strains and cyanobacterial diversity is insufficiently understood. In this respect, the increasing availability of fully sequenced bacterial genomes opens new and unprecedented opportunities to investigate the genetic inventory of organisms in the context of their pan-genome...
March 9, 2018: PLoS Genetics
Guotao Peng, Robbie Martin, Stephen Dearth, Xiaocun Sun, Gregory L Boyer, Shawn Campagna, Sijie Lin, Steven W Wilhelm
Freshwater cyanobacterial blooms are regularly formed by Microcystis spp., which are well-known producers of the hepatotoxin microcystin. The environmental factors that regulate microcystin synthesis remain unclear. We used reverse transcription-quantitative PCR (RT-qPCR), metabolomics, and toxin profiling (both by LC-MS) to measure the response of Microcystis aeruginosa NIES-843 to nitrogen (N) concentration, N chemistry (nitrate vs. urea), and a range of seasonally-relevant temperatures. Growth rates at lower temperatures were slower but resulted in increased cellular microcystin content (quota), and at these lower temperatures, N concentration had no effect on toxin production...
March 9, 2018: Environmental Science & Technology
Cátia F Gonçalves, Catarina C Pacheco, Paula Tamagnini, Paulo Oliveira
Cyanobacteria were the first organisms ever to perform oxygenic photosynthesis and still significantly contribute to primary production on a global scale. To assure the proper functioning of their primary metabolism and cell homeostasis, cyanobacteria must rely on efficient transport systems to cross their multilayered cell envelope. However, cyanobacterial secretion mechanisms remain largely unknown. Here, we report on the identification of 11 putative inner membrane translocase components of TolC-mediated secretion in the unicellular cyanobacterium Synechocystis sp...
March 9, 2018: Environmental Microbiology
Ana P D Andreote, Francisco Dini-Andreote, Janaina Rigonato, Gabriela Silva Machineski, Bruno C E Souza, Laurent Barbiero, Ary T Rezende-Filho, Marli F Fiore
Soda lakes have high levels of sodium carbonates and are characterized by salinity and elevated pH. These ecosystems are found across Africa, Europe, Asia, Australia, North, Central, and South America. Particularly in Brazil, the Pantanal region has a series of hundreds of shallow soda lakes (ca. 600) potentially colonized by a diverse haloalkaliphilic microbial community. Biological information of these systems is still elusive, in particular data on the description of the main taxa involved in the biogeochemical cycling of life-important elements...
2018: Frontiers in Microbiology
Navish Kumar Batchu, Shradha Khater, Sonal Patil, Vinod Nagle, Gautam Das, Bhaskar Bhadra, Ajit Sapre, Santanu Dasgupta
A filamentous cyanobacteria, Geitlerinema sp. FC II, was isolated from marine algae culture pond at Reliance Industries Limited (RIL), India. The 6.7 Mb draft genome of FC II encodes for 6697 protein coding genes. Analysis of the whole genome sequence revealed presence of nif gene cluster, supporting its capability to fix atmospheric nitrogen. FC II genome contains two variants of sulfide:quinone oxidoreductases (SQR), which is a crucial elector donor in cyanobacterial metabolic processes. FC II is characterized by the presence of multiple CRISPR- Cas (Clustered Regularly Interspaced Short Palindrome Repeats - CRISPR associated proteins) clusters, multiple variants of genes encoding photosystem reaction centres, biosynthetic gene clusters of alkane, polyketides and non-ribosomal peptides...
March 5, 2018: Genomics
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