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Weiyang Chen, Longfa Fang, Xiahe Huang, Haitao Ge, Jinlong Wang, Xiaorong Wang, Yuanya Zhang, Na Sui, Wu Xu, Yingchun Wang
Differential expression of cold-responsive proteins is necessary for cyanobacteria to acclimate to cold stress frequently occurring in their natural habitats. Accumulating evidence indicates that cold-induced expression of certain proteins is dependent on light illumination, but a systematic identification of light-dependent and/or light-independent cold-responsive proteins in cyanobacteria is still lacking. Herein, we comprehensively identified cold-responsive proteins in a model cyanobacterium Synechocystis sp...
March 12, 2018: Journal of Proteomics
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
Sun Young Choi, Sang Jun Sim, Jong-Il Choi, Han Min Woo
To identify microbial squalene that has been widely used in various industrial applications, intracellular formation of photosynthetic squalene was investigated using the previously engineered Synechococcus elongatus PCC 7942 strain. Unlike the proposed localization of squalene in the membrane bilayer, small droplets were identified in the cytoplasm of S. elongatus PCC 7942 as squalene using transmission electron microscopy analysis. Determination of the diameters of the squalene droplets with manual examination of 1,016 droplets in different squalene-producing strains indicated larger squalene droplets in larger cells...
March 12, 2018: Letters in Applied Microbiology
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
Saratram Gopalakrishnan, Himadri B Pakrasi, Costas D Maranas
Completeness and accuracy of metabolic mapping models impacts the reliability of flux estimation in photoautotrophic systems. In this study, metabolic fluxes under photoautotrophic growth conditions in the widely-used cyanobacterium Synechocystis PCC 6803 are quantified by re-analyzing an existing dataset using genome-scale isotopic instationary13 C-Metabolic Flux Analysis (INST-MFA). The reconstructed carbon mapping model imSyn617 and implemented algorithmic updates afforded an approximately 48% reduction in computation time...
March 8, 2018: Metabolic Engineering
Sarita Pandey, Anurag Kirti, Arvind Kumar, Hema Rajaram
The ubiquitous SbcCD exonuclease complex has been shown to perform an important role in DNA repair across prokaryotes and eukaryotes. However, they have remained uncharacterized in the ancient and stress-tolerant cyanobacteria. In the cyanobacterium Anabaena sp. strain PCC7120, SbcC and SbcD homologs, defined on the basis of the presence of corresponding functional domains, are annotated as hypothetical proteins, namely Alr3988 and All4463 respectively. Unlike the presence of sbcC and sbcD genes in a bicistronic operon in most organisms, these genes were distantly placed on the chromosome in Anabaena, and found to be negatively regulated by LexA...
March 9, 2018: Functional & Integrative Genomics
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
Dharitri Borah, Sangeetha Nainamalai, Subramanian Gopalakrishnan, Jayashree Rout, Naiyf S Alharbi, Sulaiman Ali Alharbi, Thajuddin Nooruddin
Exopolysaccaharides (EPS) are carbohydrate polymers secreted by microbial cells, as a protective layer termed sheath or capsule. Their composition is variable. Optimisation of nutrient factors and the effect of some simple stresses on the ability of Cyanothece epiphytica to produce EPS were tested. Of the tested stresses, exposure to ozone for 50 s at 0.06 mg/L resulted in a relatively high EPS yield, without any damage to cell structure. EPS was characterised physicochemically. Chemically, it was found to be composed of pentoses arabinose and xylose; hexoses glucose, galactose and mannose; and the deoxyhexose fucose sugars which were sulphated and with different functional groups...
March 8, 2018: Applied Microbiology and Biotechnology
Ginga Shimakawa, Chikahiro Miyake
Oxygenic phototrophs are vulnerable to damage by reactive oxygen species (ROS) that are produced in photosystem I (PSI) by excess photon energy over the demand of photosynthetic CO2 assimilation. In plant leaves, repetitive short-pulse (rSP) illumination produces ROS to inactivate PSI. The production of ROS is alleviated by oxidation of the reaction center chlorophyll in PSI, P700, during the illumination with the short-pulse light, which is supported by flavodiiron protein (FLV). In this study, we found that in the cyanobacterium Synechocystis sp...
March 8, 2018: Photosynthesis Research
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
Satomi Arisaka, Haruna Sukigara, Takashi Osanai
Cyanobacteria are a group of prokaryotic organisms that perform oxygenic photosynthesis using a similar photosynthetic apparatus as is used in higher plants and eukaryotic algae. Cyanobacteria are also known to have a circadian rhythm. Here, we evaluated the effects on photosynthesis caused by the genetic manipulation of RpaA, which is a response regulator of a two-component regulatory system responsible for the signal output from circadian clocks. Using the unicellular cyanobacterium Synechocystis sp. PCC 6803, photosynthetic activities and transcript levels of photosystem I and photosystems II in the rpaA-overexpressing strain were measured, and it was found that the parameters, such as Fv /Fm , Fv '/Fm ', qP, and ϕII, obtained from chlorophyll fluorescence analysis were decreased by rpaA overexpression...
March 5, 2018: Journal of Bioscience and Bioengineering
Victor Zarantonello, Thiago P Silva, Natália P Noyma, Juliana P Gamalier, Mariana M Mello, Marcelo M Marinho, Rossana C N Melo
Secretion of membrane-limited vesicles, collectively termed extracellular vesicles (EVs), is an important biological process of both eukaryotic and prokaryotic cells. This process has been observed in bacteria, but remains to be better characterized at high resolution in cyanobacteria. In the present work, we address the release of EVs by Cylindrospermopsis raciborskii (CYRF-01), a filamentous bloom-forming cyanobacterium, exposed to environmental stressors. First, non-axenic cultures of C. raciborskii (CYRF-01) were exposed to ultraviolet radiation (UVA + UVB) over a 6 h period, which is known to induce structural damage to this species...
2018: Frontiers in Microbiology
Neelam Dubey, Prashant Singh, Suvendra Nath Bagchi
Unbranched heterocytous cyanobacteria produce a number of serine peptidases. We have characterized several peptidases in the cell-free extracts of a true-branched N2 -fixing cyanobacterium, Westiellopsis ramosa sp. nov. Upon substrate-gel zymography of intact filaments and heterocytes, five peptidase bands were resolved, whereas in vegetative cells, a single band was discernible. No band was detected in [Formula: see text]-grown cultures suggesting that the peptidases were present under diazotrophic conditions with much of them confined to heterocytes...
March 2018: Physiology and Molecular Biology of Plants: An International Journal of Functional Plant Biology
Yamato Yoshida
The endosymbiosis of a free-living cyanobacterium into an ancestral eukaryote led to the evolution of the chloroplast (plastid) more than one billion years ago. Given their independent origins, plastid proliferation is restricted to the binary fission of pre-existing plastids within a cell. In the last 25 years, the structure of the supramolecular machinery regulating plastid division has been discovered, and some of its component proteins identified. More recently, isolated plastid-division machineries have been examined to elucidate their structural and mechanistic details...
March 4, 2018: International Journal of Molecular Sciences
Alice Jara De Porcellinis, Hanne Nørgaard, Laura Maria Furelos Brey, Simon Matthé Erstad, Patrik R Jones, Joshua L Heazlewood, Yumiko Sakuragi
Cyanobacteria fix atmospheric CO2 to biomass and through metabolic engineering can also act as photosynthetic factories for sustainable productions of fuels and chemicals. The Calvin Benson cycle is the primary pathway for CO2 fixation in cyanobacteria, algae and C3 plants. Previous studies have overexpressed the Calvin Benson cycle enzymes, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) and bifunctional sedoheptulose-1,7-bisphosphatase/fructose-1,6-bisphosphatase (hereafter BiBPase), in both plants and algae, although their impacts on cyanobacteria have not yet been rigorously studied...
March 3, 2018: Metabolic Engineering
Takuya Sugawara, Mariko Chinzei, Setsuko Numano, Chifumi Kitazaki, Munehiko Asayama
OBJECTIVE: A novel filamentous cyanobacterium, a photosynthesizing microorganism, was isolated from a river, and its unique features of flocculation and pentadecane production were characterized. RESULTS: Microscopic observations and a phylogenetic analysis with 16S rDNA revealed that this strain was a Limnothrix species denoted as the SK1-2-1 strain. Auto cell-flocculation was observed when this strain was exposed to a two-step incubation involving a standing cultivation following a shaking preincubation...
March 5, 2018: Biotechnology Letters
Travis C Korosh, Andrew Dutcher, Brian F Pfleger, Katherine D McMahon
Sidestreams in wastewater treatment plants can serve as concentrated sources of nutrients (i.e., nitrogen and phosphorus) to support the growth of photosynthetic organisms that ultimately serve as feedstock for production of fuels and chemicals. However, other chemical characteristics of these streams may inhibit growth in unanticipated ways. Here, we evaluated the use of liquid recovered from municipal anaerobic digesters via gravity belt filtration as a nutrient source for growing the cyanobacterium Synechococcus sp...
January 2018: MSphere
Kam-Chau Wu, Kin-Chung Ho, Chin-Cheung Tang, Yiu-Hung Yau
Foodwaste leachate (FWL) is often generated during foodwaste treatment processes. Owing to its high nutrient content, FWL has high potential for phycoremediation, a microalgal technology application for water treatment while acting as CO2 fixation tank. Additionally, the end product of microalgal from phycoremediation can be potentially used for biodiesel production. Therefore, the phycoremediation has drawn a lot of attention in recent decades. This study evaluates the performance of microalgal foodwaste leachate treatment and the potential of utilizing FWL as medium for microalgal biodiesel production...
March 4, 2018: Environmental Science and Pollution Research International
Rui Miao, Hao Xie, Felix Ho, Peter Lindblad
Protein engineering is a powerful tool to modify e.g. protein stability, activity and substrate selectivity. Heterologous expression of the enzyme α-ketoisovalerate decarboxylase (Kivd) in the unicellular cyanobacterium Synechocysits PCC 6803 results in cells producing isobutanol and 3-methyl-1-butanol, with Kivd identified as a potential bottleneck. In the present study, we used protein engineering of Kivd to improve isobutanol production in Synechocystis PCC 6803. Isobutanol is a flammable compound that can be used as a biofuel due to its high energy density and suitable physical and chemical properties...
March 1, 2018: Metabolic Engineering
Kati Thiel, Edita Mulaku, Hariharan Dandapani, Csaba Nagy, Eva-Mari Aro, Pauli Kallio
BACKGROUND: Photosynthetic cyanobacteria have been studied as potential host organisms for direct solar-driven production of different carbon-based chemicals from CO2 and water, as part of the development of sustainable future biotechnological applications. The engineering approaches, however, are still limited by the lack of comprehensive information on most optimal expression strategies and validated species-specific genetic elements which are essential for increasing the intricacy, predictability and efficiency of the systems...
March 2, 2018: Microbial Cell Factories
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