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Albert Collins Nganou Assonkeng, Noam Adir, Martin Mkandawire
Understanding of electronic energy transition (EET) mechanisms from the light-harvesting unit to the reaction centre in a natural system has been limited by; (a) the use of conventional transient time-resolved spectroscopy at room temperature, which result in high signal-to-noise ratio; and (b) examining extracts instead of intact light-harvesting units. Here, we report previously unknown differences and new insight in EET of two cyanobacteria species, Acaryochloris marina and Thermosynechoccocus vulvanus, which have been found only after using Uv-vis, hole-burning and fluorescence spectroscopy at ultra-low temperature and examining their intact light-harvesting unit, phycobilisomes (PBS)...
February 19, 2018: Journal of Physical Chemistry. B
Wei Du, Joeri A Jongbloets, Coco van Boxtel, Hugo Pineda Hernández, David Lips, Brett G Oliver, Klaas J Hellingwerf, Filipe Branco Dos Santos
Background: Microbial bioengineering has the potential to become a key contributor to the future development of human society by providing sustainable, novel, and cost-effective production pipelines. However, the sustained productivity of genetically engineered strains is often a challenge, as spontaneous non-producing mutants tend to grow faster and take over the population. Novel strategies to prevent this issue of strain instability are urgently needed. Results: In this study, we propose a novel strategy applicable to all microbial production systems for which a genome-scale metabolic model is available that aligns the production of native metabolites to the formation of biomass...
2018: Biotechnology for Biofuels
Natália V Casquilho, Maria Diana Moreira-Gomes, Clarissa B Magalhães, Renata T Okuro, Victor Hugo Ortenzi, Emanuel K Feitosa-Lima, Lidia M Lima, Eliezer J Barreiro, Raquel M Soares, Sandra M F O Azevedo, Samuel S Valença, Rodrigo S Fortunato, Alysson Roncally Carvalho, Walter A Zin
Microcystins-LR (MC-LR) is a cyanotoxin produced by cyanobacteria. We evaluated the antioxidant potential of LASSBio-596 (LB-596, inhibitor of phosphodiesterases 4 and 5), per os, and biochemical markers involved in lung and liver injury induced by exposure to sublethal dose of MC-LR. Fifty male Swiss mice received an intraperitoneal injection of 60 μL of saline (CTRL group, n = 20) or a sublethal dose of MC-LR (40 μg/kg, TOX group, n = 20). After 6 h the animals received either saline (TOX and CTRL groups) or LB-596 (50 mg/kg, TOX + LASS group, n = 10) by gavage...
February 15, 2018: Toxicon: Official Journal of the International Society on Toxinology
Jason Dexter, Dariusz Dziga, Jing Lv, Junqi Zhu, Wojciech Strzalka, Anna Maksylewicz, Magdalena Maroszek, Sylwia Marek, Pengcheng Fu
In this report, we establish proof-of-principle demonstrating for the first time genetic engineering of a photoautotrophic microorganism for bioremediation of naturally occurring cyanotoxins. In model cyanobacterium Synechocystis sp. PCC 6803 we have heterologously expressed Sphingopyxis sp. USTB-05 microcystinase (MlrA) bearing a 23 amino acid N-terminus secretion peptide from native Synechocystis sp. PCC 6803 PilA (sll1694). The resultant whole cell biocatalyst displayed about 3 times higher activity against microcystin-LR compared to a native MlrA host (Sphingomonas sp...
February 14, 2018: Environmental Pollution
Amanda Burson, Maayke Stomp, Emma Greenwell, Julia Grosse, Jef Huisman
A key challenge in ecology is to understand how nutrients and light affect the biodiversity and community structure of phytoplankton and plant communities. According to resource competition models, ratios of limiting nutrients are major determinants of the species composition. At high nutrient levels, however, species interactions may shift to competition for light, which might make nutrient ratios less relevant. The "nutrient-load hypothesis" merges these two perspectives, by extending the classic model of competition for two nutrients to include competition for light...
February 17, 2018: Ecology
Xianlei Cai, Ling Yao, Qiyue Sheng, Luyao Jiang, Randy A Dahlgren, Ting Wang
Bacterial communities of biofilms growing on artificial substrates were examined at two time periods (7 and 14 days) and two locations (lentic and lotic areas) in a hypereutrophic urban river of eastern China. Previous studies in this river network indicated that variations of microbial communities were the major factor affecting the distribution of antibiotic resistant genes highlighting the importance of understanding controls of microbial communities. Bacterial communities associated with biofilms were determined using epifluorescence microscopy and high-throughput sequencing...
February 16, 2018: AMB Express
Ekaterina Pushkareva, Igor S Pessi, Zorigto Namsaraev, Marie-Jose Mano, Josef Elster, Annick Wilmotte
Molecular and morphological methods were applied to study cyanobacterial community composition in biological soil crusts (BSCs) from four areas (two nunataks and two ridges) in the Sør Rondane Mountains, Antarctica. The sampling sites serve as control areas for open top chambers (OTCs) that were put in place in 2010 at the time of sample collection and will be compared with BSC samples taken from the OTCs in the future. Cyanobacterial cell biovolume was estimated using epifluorescence microscopy, which revealed the dominance of filamentous cyanobacteria in all studied sites except the Utsteinen ridge, where unicellular cyanobacteria were the most abundant...
February 7, 2018: Systematic and Applied Microbiology
Christopher L Follett, Stephanie Dutkiewicz, David M Karl, Keisuke Inomura, Michael J Follows
In the North Pacific Subtropical Gyre (NPSG), an annual pulse of sinking organic carbon is observed at 4000 m between July and August, driven by large diatoms found in association with nitrogen fixing, heterocystous, cyanobacteria: Diatom-Diazotroph Associations (DDAs). Here we ask what drives the bloom of DDAs and present a simplified trait-based model of subtropical phototroph populations driven by observed, monthly averaged, environmental characteristics. The ratio of resource supply rates favors nitrogen fixation year round...
February 15, 2018: ISME Journal
Yujiao Wang, Yanqiu Cao, Hongmei Li, Aijun Gong, Jintao Han, Zhen Qian, Wenran Chao
Microcystins (MCs) is a kind of hepatotoxin, which is the secondary metabolite of cyanobacteria. Bi 2 O 2 CO 3 (BOC) is a kind of cheap and nontoxic semiconductor material. BOC was synthetized by solvothermal method and then microcystin-LR (MC-LR) and microcystin-RR (MC-RR) were removed by BOC, through adsorption and photocatalytic degradation. When the dosage of BOC is 6 g/L, the MC-LR and MC-RR in the natural water sample can be completely adsorbed in 30 min and then after 12 h irradiation, MC-LR and MC-RR were photocatalytically degraded by BOC...
February 14, 2018: Environmental Science and Pollution Research International
Hao Zhang, Mingxu Shao, He Huang, Shujuan Wang, Lili Ma, Huining Wang, Liping Hu, Kai Wei, Ruiliang Zhu
The sheep intestinal tract is characterized by a diverse microbial ecosystem that is vital for the host to digest diet material. The importance of gut microbiota (GM) of animals has also been widely acknowledged because of its pivotal roles in the health and well-being of animals. However, there are no relevant studies on GM of small-tail Han sheep, a superior mutton variety domestic in China. In this study, the structure and distribution of gut microflora were studied by high-throughput sequencing technology...
2018: Frontiers in Microbiology
Stefanie Maier, Alexandra Tamm, Dianming Wu, Jennifer Caesar, Martin Grube, Bettina Weber
Biological soil crusts (biocrusts) cover about 12% of the Earth's land masses, thereby providing ecosystem services and affecting biogeochemical fluxes on a global scale. They comprise photoautotrophic cyanobacteria, algae, lichens and mosses, which grow together with heterotrophic microorganisms, forming a model system to study facilitative interactions and assembly principles in natural communities. Biocrusts can be classified into cyanobacteria-, lichen-, and bryophyte-dominated types, which reflect stages of ecological succession...
February 14, 2018: ISME Journal
Jonna E Teikari, David P Fewer, Rashmi Shrestha, Shengwei Hou, Niina Leikoski, Minna Mäkelä, Asko Simojoki, Wolfgang R Hess, Kaarina Sivonen
Nodularia spumigena is a nitrogen-fixing cyanobacterium that forms toxic blooms in the Baltic Sea each summer and the availability of phosphorous is an important factor limiting the formation of these blooms. Bioinformatic analysis identified a phosphonate degrading (phn) gene cluster in the genome of N. spumigena suggesting that this bacterium may use phosphonates as a phosphorus source. Our results show that strains of N. spumigena could grow in medium containing methylphosphonic acid (MPn) as the sole source of phosphorous and released methane when growing in medium containing MPn...
February 14, 2018: ISME Journal
Joseph M Jez
Plants and their green cousins cyanobacteria and algae use sunlight to drive the chemistry that lets them grow, survive, and perform an amazing range of biochemical reactions. The ability of these organisms to use a freely available energy source makes them attractive for use as sustainable and renewable platforms for more than just food production. They are also a source of metabolic tools for engineering microbes for "green" chemistry. This thematic collection of mini-reviews discusses how green organisms capture light and protect their photosynthetic machinery from too much light, new structural snapshots of the clock complex that orchestrates signaling during the light/dark cycle, challenges for improving stress responses in crops, harnessing cyanobacteria for as sustainable factories, and efforts to engineer microbes for "green" biopolymer production...
February 14, 2018: Journal of Biological Chemistry
Javier Espinosa, José I Labella, Raquel Cantos, Asunción Contreras
Cyanobacteria, phototrophic organisms performing oxygenic photosynthesis, must adapt their metabolic processes to the challenges imposed by the succession of days and nights. Two conserved cyanobacterial proteins, PII and PipX, function as hubs of the nitrogen interaction network, forming complexes with a variety of diverse targets. While PII proteins are found in all three domains of life as integrators of signals of the nitrogen and carbon balance, PipX proteins are unique to cyanobacteria, where they provide a mechanistic link between PII signalling and the control of gene expression by the global nitrogen regulator NtcA...
February 14, 2018: Environmental Microbiology
Jeffrey A Swan, Susan Golden, Andy LiWang, Carrie L Partch
Circadian rhythms enable cells and organisms to coordinate their physiology with the cyclic environmental changes that come as a result of Earth's light/dark cycles. Cyanobacteria make use of a post-translational oscillator (PTO) to maintain circadian rhythms, and this elegant system has become an important model for the post-translational timing mechanisms. Comprised of three proteins, the KaiABC system undergoes an oscillatory biochemical cycle that provides timing cues to achieve a 24-hour molecular clock...
February 13, 2018: Journal of Biological Chemistry
Minli Xu, Jeffrey G Lawrence, Dannie Durand
Highly Iterated Palindrome 1 (HIP1, GCGATCGC) is hyper-abundant in most cyanobacterial genomes. In some cyanobacteria, average HIP1 abundance exceeds one motif per gene. Such high abundance suggests a significant role in cyanobacterial biology. However, 20 years of study have not revealed whether HIP1 has a function, much less what that function might be. We show that HIP1 is 15- to 300-fold over-represented in genomes analyzed. More importantly, HIP1 sites are conserved both within and between open reading frames, suggesting that their overabundance is maintained by selection rather than by continual replenishment by neutral processes, such as biased DNA repair...
February 8, 2018: Nucleic Acids Research
Anke Schwarzenberger, Patrick Fink
Food quality is an important factor influencing organisms' well-being. In freshwater ecosystems, food quality has been studied extensively for the keystone herbivore genus Daphnia, as they form the critical trophic link between primary producers and higher order consumers such as fish. For Daphnia, the edible fraction of phytoplankton in lakes (consisting mostly of unicellular algae and cyanobacteria) is extraordinarily diverse. To be able to digest different food particles, Daphnia possess a set of digestive enzymes that metabolize carbohydrates, lipids and proteins...
February 7, 2018: Comparative Biochemistry and Physiology. Part B, Biochemistry & Molecular Biology
G C du Preez, V Wepener, H Fourie, M S Daneel
Ensuring food security is becoming increasingly difficult due to limited freshwater resources. Low-quality irrigation water also poses a severe threat to crop yield and quality. The aim of this study was to evaluate the water quality associated with the Crocodile (West) and Marico catchments, which represent one of South Africa's most developed regions. Sources of irrigation water include the hypertrophic Hartbeespoort Dam, as well as the heavily impacted Crocodile (West) River. Analysis of historical irrigation water quality data (from January 2005 to December 2015) revealed that the Hartbeespoort and Crocodile (West) irrigation schemes were exposed to calcium sulfate enrichment, likely as a result of extensive mining activities in the Bushveld Igneous Complex...
February 9, 2018: Environmental Monitoring and Assessment
Catherine Gérikas Ribeiro, Adriana Lopes Dos Santos, Dominique Marie, Frederico Pereira Brandini, Daniel Vaulot
Symbioses between eukaryotic algae and nitrogen-fixing cyanobacteria have been recognized in recent years as a key source of new nitrogen in the oceans. We investigated the composition of the small photosynthetic eukaryote communities associated with nitrogen-fixing cyanobacteria in the Brazilian South Atlantic Bight using a combination of flow cytometry sorting and high throughput sequencing of two genes: the V4 region of 18S rRNA and nifH. Two distinct eukaryotic communities were often encountered, one dominated by the Mamiellophyceae Bathycoccus and Ostreococcus, and one dominated by a prymnesiophyte known to live in symbiosis with the UCYN-A1 nitrogen-fixing cyanobacterium...
February 9, 2018: ISME Journal
Lan Wang, Jing Zhang, Huilin Li, Hong Yang, Chao Peng, Zhengsong Peng, Lu Lu
Urban rivers represent a unique ecosystem in which pollution occurs regularly, leading to significantly altered of chemical and biological characteristics of the surface water and sediments. However, the impact of urbanization on the diversity and structure of the river microbial community has not been well documented. As a major tributary of the Yangtze River, the Jialing River flows through many cities. Here, a comprehensive analysis of the spatial microbial distribution in the surface water and sediments in the Nanchong section of Jialing River and its two urban branches was conducted using 16S rRNA gene-based Illumina MiSeq sequencing...
January 30, 2018: Science of the Total Environment
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