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1.
Chem Commun (Camb) ; 55(76): 11410-11413, 2019 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-31482869

RESUMO

Graphene-based composite materials are versatile but not easily procurable. Cyanobacterial cells, an outgrowth of eutrophic freshwater lake, were simultaneously employed as a template for the growth of ZnO nanoparticles and as a biomass carbon source for graphene sheets, resulting in chlorophyll-containing graphene-wrapped ZnO nanospheres.


Assuntos
Cianobactérias/química , Cianobactérias/citologia , Grafite/química , Nanosferas/química , Óxido de Zinco/química , Clorofila/química
2.
Sci Total Environ ; 671: 329-338, 2019 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-30933789

RESUMO

Hydrodynamic conditions are closely related to the development and dissipation of cyanobacterial blooms. The morphological features of Dolichospermum under different hydrodynamic conditions were analysed during three blooms in Gaoyang Lake, which is part of the backwater area of the China Three Gorges Reservoir, from 2007 to 2010. The results showed that the length of filaments and the morphology of cells were different in relation to the turbulence caused by the difference in hydraulic retention times. Thus, it was hypothesized that turbulence could shape the morphology and physiology of cyanobacteria. To answer the question regarding what the morphological and physiological responses of cyanobacteria to turbulent mixing mean for these organisms, laboratory experiments in continuous cultivation under different dilution rates were conducted to analyse the effects of specific turbulence intensity on the growth, nutrient uptake and morphology of Dolichospermum flos-aquae. Increasing the turbulence intensity caused synchronous increases in the ratio of the cellular length to the width, in the specific surface area of the filament and the cell and in the nutrient uptake rate; at the same time, the average filament length decreased. These indicated that the turbulence, within the range of our experimental design, could stimulate the growth of Dolichospermum by increasing its nutrient uptake. Additionally, at a high specific growth rate, the nutrient uptake rate of Dolichospermum changed more noticeably with the increasing morphological indicators, indicating that the rapidly growing Dolichospermum was more sensitive to turbulence. These findings explain the role of morphological strategies in the dominance of Dolichospermum within a certain range of turbulence intensity, especially in the early growth stage of blooms. The results also facilitate a greater understanding of the hydrodynamic effects on cyanobacteria and will be instrumental in developing flow regulation to control cyanobacterial blooms in reservoirs.


Assuntos
Cianobactérias/fisiologia , Eutrofização , Lagos/microbiologia , China , Cianobactérias/citologia , Monitoramento Ambiental , Hidrodinâmica , Nutrientes/metabolismo
3.
Ecotoxicol Environ Saf ; 174: 584-591, 2019 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-30870659

RESUMO

Single and multispecies algal bioassays were assessed using copper toxicity with three green algae (Scenedesmus subspicatus, Scenedesmus quadricauda and Ankistrodesmus angustus) and one blue-green algae species (Oscillatoria prolifera). Single and multispecies toxicity tests were conducted based on cell density as per standard toxicity testing, and on equivalent surface area. A higher copper sulfate toxicity was registered for O. prolifera, followed by S. subspicatus, S. quadricauda, and A. angustus in single-species toxicity tests based on cell density. Single species toxicity tests based on surface area showed increased copper toxicity with increasing algal surface area except for A. angustus. In multispecies control bioassays, the growth of A. angustus was inhibited in the presence of other species in surface area-based tests. As compared to single species bioassays, O. prolifera, and S. quadricauda showed a decreased sensitivity to copper sulfate in both cell density and surface area based multispecies tests. However, for the algae species with the smallest surface area, S. subspicatus, 96h-EC50 value decreased in multispecies bioassays based on surface area as compared to the single species test, while it increased in multispecies bioassays based on cell density. The difference in S. subspicatus sensitivity to copper between tests based on cell density and surface area supports the need to adopt multispecies toxicity testing based on surface area to avoid the confounding effect on copper toxicity of increased biomass for metal binding. 96h-EC50 values for all species combined in the multispecies test based on cell density and on surface area were significantly different from 96h-EC50 values obtained in single species bioassays. These results demonstrate that single-species bioassays may over- or underestimate metal toxicity in natural waters.


Assuntos
Clorófitas/efeitos dos fármacos , Sulfato de Cobre/toxicidade , Herbicidas/toxicidade , Bioensaio , Contagem de Células , Clorófitas/citologia , Clorófitas/crescimento & desenvolvimento , Cianobactérias/citologia , Cianobactérias/efeitos dos fármacos , Cianobactérias/crescimento & desenvolvimento , Scenedesmus/citologia , Scenedesmus/efeitos dos fármacos , Scenedesmus/crescimento & desenvolvimento , Testes de Toxicidade
4.
ISME J ; 13(5): 1133-1143, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30607028

RESUMO

Here we aim to incorporate trait-based information into the modern coexistence framework that comprises a balance between stabilizing (niche-based) and equalizing (fitness) mechanisms among interacting species. Taking the modern coexistence framework as our basis, we experimentally tested the effect of size differences among species on coexistence by using fifteen unique pairs of resident vs. invading cyanobacteria, resulting in thirty unique invasibility tests. The cyanobacteria covered two orders of magnitude differences in size. We found that both niche and fitness differences increased with size differences. Niche differences increased faster with size differences than relative fitness differences and whereas coexisting pairs showed larger size differences than non-coexisting pairs, ultimately species coexistence could not be predicted on basis of size differences only. Our findings suggest that size is more than a key trait controlling physiological and population-level aspects of phytoplankton, it is also relevant for community-level phenomena such as niche and fitness differences which influence coexistence and biodiversity.


Assuntos
Cianobactérias/fisiologia , Fitoplâncton/fisiologia , Biodiversidade , Cianobactérias/citologia , Ecossistema , Aptidão Genética , Fenótipo , Fitoplâncton/citologia
5.
J Biosci Bioeng ; 127(2): 213-221, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30391236

RESUMO

Synergistic coexistence of nitrogen fixing cyanobacteria such as Anabaena variabilis, Nostoc muscorum and Westiellopsis prolifica with green algae namely Scenedesmus obliquus, Chlorella vulgaris and Botryococcus braunii was studied under nitrogen deficient conditions. The effect of these interactions was investigated on growth, fixed nitrogen content, lipid content and their secretomes in individual cultures and cocultures. Based on the cocultivation studies, it was found that out of the nine interactions studied, B. braunii-N. muscorum synergism was best established. This interaction resulted in a maximum of 50% enhancement in nitrogen fixation in B. braunii-N. muscorum co-culture leading to 27% enhancement in lipid content (membrane and neutral lipid). In general, B. braunii co-cultures showed an enhancement in biomass content of up to 38%. Secretome analysis showed presence of new and modified secondary metabolites having roles in quorum sensing/quenching, interspecies signaling, N-fixation, carbon metabolism, lipid metabolism, antimicrobial activity. Compounds such as trichloroacetic acid and hexadecane were identified that are known to have roles in nitrogen assimilation and carbon metabolism, respectively, were present in some of the co-culture secretomes. The combination of B. braunii-N. muscorum led to the formation of new compounds such as triacontanol which have role in improvement of glucose-lipid metabolism and 9-octadecenamide that is known to be a phytohormone.


Assuntos
Clorófitas/crescimento & desenvolvimento , Clorófitas/metabolismo , Cianobactérias/crescimento & desenvolvimento , Cianobactérias/metabolismo , Metaboloma , Interações Microbianas/fisiologia , Via Secretória , Biomassa , Metabolismo dos Carboidratos , Chlorella vulgaris/citologia , Chlorella vulgaris/crescimento & desenvolvimento , Chlorella vulgaris/metabolismo , Clorófitas/citologia , Técnicas de Cocultura/métodos , Cianobactérias/citologia , Metabolismo dos Lipídeos , Lipídeos/análise , Metabolômica/métodos , Técnicas Microbiológicas/métodos , Nitrogênio/metabolismo , Fixação de Nitrogênio
6.
Chemosphere ; 215: 693-702, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30347364

RESUMO

Ionic silver is a potential hazard to aquatic life forms because of the increasing usage of silver based materials. The need for developing a sustainable and ecofriendly process to minimize the toxic effects of the free ions burden is now a scientific consensus. Therefore, we report the latest results in cyanobacterium Leptolyngbya JSC-1 investigating the tolerance towards toxic doses of silver, its extracellular biomineralization and silver nano-deposits formation inside the cells, and speculate about potential environmental impacts. In this study, scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) analysis reveal the extracellular biomineralization of soluble silver (1-100 µM) into corresponding nanoparticles (50-100 nm in diameter) by JSC-1, while X-ray photoelectron spectroscopy (XPS) examination divulged the presence of both Ag+ and Ag0 in extracellularly biomineralized silver, depicting a mixture of both AgxO and elemental Ag. The scanning transmission electron microscopy (STEM), EDS and elemental mapping visualized the formation of intracellular silver nanoparticles. Moreover, this feature of silver tolerance in JSC-1 was further exploited and a novel protocol was developed for isolation and maintenance of axenic culture of this filamentous cyanobacterium. Consequently, this capability of silver biomineralization by JSC-1, both extra- and intra-cellularly might be useful for modeling the Ag resistance mechanism in cyanobacteria and also might be a sustainable alternative for heavy metals bioremediation in aquatic environments.


Assuntos
Cultura Axênica/métodos , Cianobactérias/metabolismo , Prata/química , Biodegradação Ambiental , Cianobactérias/citologia , Íons/química , Íons/toxicidade , Nanopartículas Metálicas/química , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Espectroscopia Fotoeletrônica , Prata/toxicidade , Espectrometria por Raios X
7.
Extremophiles ; 23(1): 35-48, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30284641

RESUMO

Genotypic and morphological diversity of cyanobacteria in the Rupite hot spring (Bulgaria) was investigated by means of optical microscopy, cultivation, single-cell PCR, and 16S rRNA gene amplicon sequencing. Altogether, 34 sites were investigated along the 71-39 °C temperature gradient. Analysis of samples from eight representative sites shown that Illumina, optical microscopy, and Roche 454 identified 72, 45 and 19% respective occurrences of all cumulatively present taxa. Optical microscopy failed to detect species of minor occurrence; whereas, amplicon sequencing technologies suffered from failed primer annealing and the presence of species with extensive extracellular polysaccharides production. Amplicon sequencing of the 16S rRNA gene V5-V6 region performed by Illumina identified the cyanobacteria most reliably to the generic level. Nevertheless, only the combined use of optical microscopy, cultivation and sequencing methods allowed for reliable estimate of the cyanobacterial diversity. Here, we show that Rupite hot-spring system hosts one of the richest cyanobacterial flora reported from a single site above 50 °C. Chlorogloeopsis sp. was the most abundant at the highest temperature (68 °C), followed by Leptolyngbya boryana, Thermoleptolyngbya albertanoae, Synechococcus bigranulatus, Oculatella sp., and Desertifilum sp. thriving above 60 °C, while Leptolyngbya geysericola, Geitlerinema splendidum, and Cyanobacterium aponinum were found above 50 °C.


Assuntos
Cianobactérias/genética , Fontes Termais/microbiologia , Microbiota , Cianobactérias/classificação , Cianobactérias/citologia , Cianobactérias/isolamento & purificação , RNA Ribossômico 16S/genética
8.
Phytochemistry ; 157: 206-218, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30447471

RESUMO

Cyanobacteria are mainly known to incorporate inorganic molecules like carbon dioxide and ammonia from the environment into organic material within the cell. Nevertheless cyanobacteria do import and export organic substances through the cytoplasmic membrane and these processes are essential for all cyanobacteria. In addition understanding the mechanisms of transport of organic molecules through the cytoplasmic membrane might become very important. Genetically modified strains of cyanobacteria could serve as producers and exporters of commercially important substances. In this review we attempt to present all data of transport of organic molecules through the cytoplasmic membrane of cyanobacteria that are currently available with the transported molecules ordered according to their chemical classes.


Assuntos
Membrana Celular/metabolismo , Cianobactérias/citologia , Compostos Orgânicos/metabolismo , Transporte Biológico , Imunidade Celular
9.
RNA Biol ; 16(4): 518-529, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-29995583

RESUMO

Novel CRISPR-Cas systems possess substantial potential for genome editing and manipulation of gene expression. The types and numbers of CRISPR-Cas systems vary substantially between different organisms. Some filamentous cyanobacteria harbor > 40 different putative CRISPR repeat-spacer cassettes, while the number of cas gene instances is much lower. Here we addressed the types and diversity of CRISPR-Cas systems and of CRISPR-like repeat-spacer arrays in 171 publicly available genomes of multicellular cyanobacteria. The number of 1328 repeat-spacer arrays exceeded the total of 391 encoded Cas1 proteins suggesting a tendency for fragmentation or the involvement of alternative adaptation factors. The model cyanobacterium Anabaena sp. PCC 7120 contains only three cas1 genes but hosts three Class 1, possibly one Class 2 and five orphan repeat-spacer arrays, all of which exhibit crRNA-typical expression patterns suggesting active transcription, maturation and incorporation into CRISPR complexes. The CRISPR-Cas system within the element interrupting the Anabaena sp. PCC 7120 fdxN gene, as well as analogous arrangements in other strains, occupy the genetic elements that become excised during the differentiation-related programmed site-specific recombination. This fact indicates the propensity of these elements for the integration of CRISPR-cas systems and points to a previously not recognized connection. The gene all3613 resembling a possible Class 2 effector protein is linked to a short repeat-spacer array and a single tRNA gene, similar to its homologs in other cyanobacteria. The diversity and presence of numerous CRISPR-Cas systems in DNA elements that are programmed for homologous recombination make filamentous cyanobacteria a prolific resource for their study. Abbreviations: Cas: CRISPR associated sequences; CRISPR: Clustered Regularly Interspaced Short Palindromic Repeats; C2c: Class 2 candidate; SDR: small dispersed repeat; TSS: transcriptional start site; UTR: untranslated region.


Assuntos
Sistemas CRISPR-Cas/genética , Cianobactérias/citologia , Cianobactérias/genética , Sequência de Bases , Diferenciação Celular/genética , Regulação Bacteriana da Expressão Gênica , Recombinação Homóloga/genética , Filogenia , Sintenia/genética
10.
Biochim Biophys Acta Bioenerg ; 1860(1): 78-88, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30414930

RESUMO

Photosynthetic pigment-protein complexes are highly concentrated in thylakoid membranes of chloroplasts and cyanobacteria that emit strong autofluorescence (mainly 600-800 nm). In Raman scattering microscopy that enables imaging of pigment concentrations of thylakoid membranes, near infrared laser excitation at 1064 nm or visible laser excitation at 488-532 nm has been often employed in order to avoid the autofluorescence. Here we explored a new approach to Raman imaging of thylakoid membranes by using excitation wavelength of 976 nm. Two types of differentiated cells, heterocysts and vegetative cells, in two diazotrophic filamentous cyanobacteria, Anabaena variabilis, and Rivularia M-261, were characterized. Relative Raman scattering intensities of phycobilisomes of the heterocyst in comparison with the nearest vegetative cells of Rivularia remained at a significantly higher level than those of A. variabilis. It was also found that the 976 nm excitation induces photoluminescence around 1017-1175 nm from the two cyanobacteria, green alga (Parachlorella kessleri) and plant (Arabidopsis thaliana). We propose that this photoluminescence can be used as an index of concentration of chlorophyll a that has relatively small Raman scattering cross-sections. The Rivularia heterocysts that we analyzed were clearly classified into at least two subgroups based on the Chla-associated photoluminescence and carotenoid Raman bands, indicating two physiologically distinct states in the development or aging of the terminal heterocyst.


Assuntos
Técnicas Citológicas/métodos , Medições Luminescentes , Análise Espectral Raman , Arabidopsis/citologia , Senescência Celular , Clorofila A/análise , Clorófitas/citologia , Cianobactérias/citologia , Técnicas Citológicas/instrumentação , Ficobilissomas/análise , Tilacoides
11.
Environ Monit Assess ; 191(1): 29, 2018 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-30591969

RESUMO

In this paper, the algal cell density of cyanobacteria, green algae, and diatoms and their responses to the hydrochemical factors were analyzed to reveal the structural characteristics of water quality in an urban river. A total of nine sampling sites from upstream to downstream was explored in our study. At each site, the density of algae was identified every week during the wet season (June-October) from 2012 to 2017, and in situ detection was used for the relative 11 hydrochemical variables. The temporal and spatial characteristics of 14 variables were analyzed using a heatmap coupled with the cluster analysis method. The trend of each parameter was analyzed using the smoothing method with locally weighted regression. The nonmetric multidimensional scaling method was employed to detect the temporal and spatial similarities among algae along hydrochemical gradients. The responses of algal density to hydrochemical variables were analyzed using a redundancy analysis. The results showed that the water temperature (Wtemp), pH, dissolved oxygen (DO), cyanobacteria, and diatoms exhibited significant declining trends, and significant increasing trends were shown in the permanganate index, chemical oxygen demand, total nitrogen, ammonia nitrogen, and total phosphorus; the cyanobacteria exhibited certain differences with green algae and diatoms in summer and the downstream areas of the river. The temporal-spatial homogeneity of algal to hydrochemical variables showed the key influencing factors of Wtemp for cyanobacteria density, chlorophyll for green algae density, DO, and pH for diatoms. The results presented here are valuable for deepening our understanding of river ecosystem evaluations and effective environmental management, as well as an important reference for the sustainable development of aquatic biological resources.


Assuntos
Clorófitas/citologia , Cianobactérias/citologia , Diatomáceas/citologia , Monitoramento Ambiental/métodos , Rios/química , Movimentos da Água , China , Clorofila/análise , Clorófitas/crescimento & desenvolvimento , Cianobactérias/crescimento & desenvolvimento , Diatomáceas/crescimento & desenvolvimento , Ecossistema , Eutrofização , Nitrogênio/análise , Fósforo/análise , Estações do Ano , Urbanização , Qualidade da Água
12.
Nano Lett ; 18(12): 7448-7456, 2018 12 12.
Artigo em Inglês | MEDLINE | ID: mdl-30403141

RESUMO

Investigating the multidimensional integration between different microbiological kingdoms possesses potential toward engineering next-generation bionic architectures. Bacterial and fungal kingdom exhibits mutual symbiosis that can offer advanced functionalities to these bionic architectures. Moreover, functional nanomaterials can serve as probing agents for accessing newer information from microbial organisms due to their dimensional similarities. In this article, a bionic mushroom was created by intertwining cyanobacterial cells with graphene nanoribbons (GNRs) onto the umbrella-shaped pileus of mushroom for photosynthetic bioelectricity generation. These seamlessly merged GNRs function as agents for mediating extracellular electron transport from cyanobacteria resulting in photocurrent generation. Additionally, three-dimensional (3D) printing technique was used to assemble cyanobacterial cells in anisotropic, densely packed geometry resulting in adequate cell-population density for efficient collective behavior. These 3D printed cyanobacterial colonies resulted in comparatively higher photocurrent (almost 8-fold increase) than isotropically casted cyanobacteria of similar seeding density. An insight of the proposed integration between cyanobacteria and mushroom derives remarkable advantage that arises from symbiotic relationship, termed here as engineered bionic symbiosis. Existence of this engineered bionic symbiosis was confirmed by UV-visible spectroscopy and standard plate counting method. Taken together, the present study augments scientific understanding of multidimensional integration between the living biological microworld and functional abiotic nanomaterials to establish newer dimensionalities toward advancement of bacterial nanobionics.


Assuntos
Fontes de Energia Bioelétrica/microbiologia , Cianobactérias/citologia , Nanoestruturas/química , Nanotecnologia/métodos , Impressão Tridimensional , Biônica/métodos , Células Imobilizadas/citologia , Células Imobilizadas/metabolismo , Cianobactérias/metabolismo , Transporte de Elétrons , Fotossíntese
13.
Toxicon ; 154: 1-6, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30243795

RESUMO

Eighty cultures from the Novi Sad Cyanobacterial Culture Collection (NSCCC) were screened for toxicity with Artemia salina bioassay and for common cyanobacterial toxins, microcystins/nodularin (MCs/NOD) and saxitoxin (STX), with ELISA assays. The results show that 22.5% (11) of the investigated cyanobacterial cultures in exponential phase exhibited toxicity in the A. salina bioassay and 38.7% (31) produced MCs/NOD and/or STX. However, the findings in the two methods applied were contradictory. Therefore, A. salina bioassay was repeated on 28 cultures in stationary growth phase, which were positive in ELISA assays but not in the initial A. salina bioassay. Seven more cultures exhibited cell-bound toxicity, and only one extracellular toxicity. The observed difference in the toxicity indicates that cyanobacterial growth phase could affect the screening results. The findings also varied depending on the environment from which the cultures originated. In the initial screening via bioassay, 11.8% (6 cultures out of 51) from terrestrial and 17.2% (5 out of 29) from aquatic environment showed cell-bound toxicity. Furthermore, based on the ELISA assay, 31.4% (16) of the cultures from terrestrial ecosystems were positive for the presence of the investigated cyanotoxins, and 51.7% (15) from aquatic ecosystems. Based on all results, more frequent toxin production was observed in cultures originating from aquatic environments. Furthermore, the group of terrestrial cultures that originated from biological loess crusts were basically non-toxic. The discrepancies in the results by two different methods indicates that the use of several complementary methods would help to improve the assessment of cyanobacterial toxicity and cyanotoxin analyses.


Assuntos
Toxinas Bacterianas/toxicidade , Cianobactérias/química , Cianobactérias/citologia , Toxinas Marinhas/toxicidade , Microcistinas/toxicidade , Animais , Artemia/crescimento & desenvolvimento , Cianobactérias/metabolismo , Ecossistema , Sérvia , Testes de Toxicidade/métodos
14.
Environ Sci Pollut Res Int ; 25(28): 28460-28470, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30088246

RESUMO

Relationship between phytoplankton community and environmental variables was explored in three landscape water bodies (namely Jiyun River Oxbow (JRO), Qingjing Lake (QL), and Jiyun River (JR)) with high salinity, located in Sino-Singapore Tianjin Eco-city of China, using redundancy analysis (RDA). A total of 48 species of phytoplankton were identified during the study period, in which Chlorophyta and Bacillariophyta accounted for 35.42 and 31.25%, respectively. The most dominant species of the studied water bodies were Cyclotella meneghiniana (Bacillariophyta) and Aphanocapsa elachista (Cyanophyta). The diversity index ranged from 0.56 to 1.42, with an average of 1.11, reflecting low biodiversity in the phytoplankton community. Moreover, the average density of phytoplankton was 42.39 × 106 cells/L, indicating that those landscape water bodies belonged to moderate eutrophication. The results of RDA revealed that the most significant environmental factors influencing phytoplankton community were water temperature (WT), dissolved total phosphorus (DTP), salinity, and total nitrogen (TN) (p < 0.05, Monte Carlo permutation test). Meanwhile, Aphanocapsa elachista was positively correlated with WT, TN, and salinity, while Cyclotella meneghiniana was positively related to salinity and negatively related to TP. The results suggested that salinity was a non-negligible key factor affecting the phytoplankton community of the water body with high salinity.


Assuntos
Clorófitas/crescimento & desenvolvimento , Cianobactérias/crescimento & desenvolvimento , Diatomáceas/crescimento & desenvolvimento , Água Doce/química , Fitoplâncton/crescimento & desenvolvimento , Poluentes Químicos da Água/análise , Biodiversidade , China , Clorófitas/classificação , Cianobactérias/citologia , Diatomáceas/classificação , Eutrofização , Fitoplâncton/classificação , Salinidade , Singapura
15.
J Phycol ; 54(5): 638-652, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30055049

RESUMO

Two untapered, heterocytous species were observed and collected from the intertidal and supratidal zones of the Mexican coastline of the Pacific Ocean near Oaxaca and from the Gulf of Mexico. These populations were highly similar in morphology to the freshwater taxon Petalonema incrustans in the Scytonemataceae. However, 16S rRNA sequence data and phylogenetic analysis indicated that they were sister taxa to the epiphyllic, Brazilian species Phyllonema aveceniicola in the Rivulariaceae, described from culture material. While genetic identity between the two new species was high, they differed significantly in morphology, 16S rRNA gene sequence identity, and sequence and structure of the 16S-23S ITS region. Their morphology differed markedly from the generitype of the previously monotypic Phyllonema, which has tapered, heteropolar, single-false branched trichomes with very thin or absent sheath. The two new species, Phyllonema ansata and Phyllonema tangolundensis, described from both culture and environmental material, have untapered, isopolar, geminately false branched trichomes with thick, lamellated sheaths, differences so significant that the species would not be placed in Phyllonema without molecular corroboration. The morphological differences are so significant that a formal emendation of the genus is required. These taxa provide a challenge to algal taxonomy because the morphological differences are such that one would logically conclude that they represent different genera, but the phylogenetic evidence for including them all in the same genus is conclusive. This conclusion is counter to the current trend in algal taxonomy in which taxa with minor morphological differences have been repeatedly placed in separate genera based primarily upon DNA sequence evidence.


Assuntos
Cianobactérias/classificação , Cianobactérias/citologia , Proteínas de Algas/análise , Cianobactérias/genética , Cianobactérias/ultraestrutura , DNA Espaçador Ribossômico/análise , México , Filogenia , Estrutura Secundária de Proteína , RNA de Algas/análise , RNA Ribossômico 16S/análise , Análise de Sequência de RNA
16.
PLoS One ; 13(5): e0196383, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29746494

RESUMO

Morphological transformations in primitive organisms have long been observed; however, its biomechanical roles are largely unexplored. In this study, we investigate the structural advantages of dimorphism in Arthrospira platensis, a filamentous multicellular cyanobacterium. We report that helical trichomes, the default shape, have a higher persistence length (Lp), indicating a higher resistance to bending or a large value of flexural rigidity (kf), the product of the local cell stiffness (E) and the moment of inertia of the trichomes' cross-section (I). Through Atomic Force Microscopy (AFM), we determined that the E of straight and helical trichomes were the same. In contrast, our computational model shows that I is greatly dependent on helical radii, implying that trichome morphology is the major contributor to kf variation. According to our estimation, increasing the helical radii alone can increase kf by 2 orders of magnitude. We also observe that straight trichomes have improved gliding ability, due to its structure and lower kf. Our study shows that dimorphism provides mechanical adjustability to the organism and may allow it to thrive in different environmental conditions. The higher kf provides helical trichomes a better nutrient uptake through advection in aquatic environments. On the other hand, the lower kf improves the gliding ability of straight trichomes in aquatic environments, enabling it to chemotactically relocate to more favorable territories when it encounters certain environmental stresses. When more optimal conditions are encountered, straight trichomes can revert to their original helical form. Our study is one of the first to highlight the biomechanical role of an overall-shape transformation in cyanobacteria.


Assuntos
Forma Celular/fisiologia , Spirulina/citologia , Spirulina/metabolismo , Fenômenos Bioquímicos , Transporte Biológico/fisiologia , Fenômenos Biomecânicos , Biofísica , Simulação por Computador , Cianobactérias/citologia , Cianobactérias/metabolismo , Cianobactérias/fisiologia , Tricomas/fisiologia
17.
Microbiol Res ; 211: 47-56, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29705205

RESUMO

A novel halotolerant species of cyanobacterium of the order Chroococcales was isolated from hypersaline estuary in Kwa-Zulu Natal, South Africa. A comprehensive polyphasic approach viz., cell morphology, pigment composition and complete genome sequence analysis was conducted to elucidate the taxonomic position of the isolated strain. The blue-green oval to rod-shaped cells were 14-18 µm in size, and contained a high amount of phycocyanin pigments. The strain was moderate thermotolerant/alkalitolerant halophile with the optimum conditions for growth at 35 °C, pH 8.5 and 120 g/l of NaCl. Based on 16S rRNA gene sequence phylogeny, the strain was related to members of the 'Euhalothece' subcluster (99%). The whole genome sequence was determined, and the annotated genes showed a 90% sequence similarity to the gas-vacuolate, spindle-shaped Dactylococcopsis salina PCC 8305. The size of the genome was determined to be 5,113,178 bp and contained 4332 protein-coding genes and 69 RNA genes with a G + C content of 46.7%. Genes encoding osmoregulation, oxidative stress, heat shock, persister cells, and UV-absorbing secondary metabolites, among others, were identified. Based on the phylogenetic analysis of the 16S rRNA gene sequences, physiological data, pigment compositions and genomic data, the strain is considered to represent a novel species of Euhalothece.


Assuntos
Cianobactérias/classificação , Cianobactérias/citologia , Cianobactérias/genética , Cianobactérias/isolamento & purificação , Genótipo , Fenótipo , Filogenia , Água do Mar/microbiologia , Técnicas de Tipagem Bacteriana , Composição de Bases , Biomassa , DNA Bacteriano/genética , DNA Bacteriano/isolamento & purificação , Genes Bacterianos/genética , Tamanho do Genoma , Proteínas de Choque Térmico/genética , Concentração de Íons de Hidrogênio , Osmorregulação/genética , Estresse Oxidativo/genética , Ficocianina/metabolismo , RNA Bacteriano/genética , RNA Ribossômico 16S/genética , Tolerância ao Sal , Análise de Sequência de DNA , Cloreto de Sódio/metabolismo , África do Sul , Especificidade da Espécie , Temperatura Ambiente , Sequenciamento Completo do Genoma
18.
Curr Biol ; 28(4): 616-622.e1, 2018 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-29398221

RESUMO

Cyanobacteria were the ultimate ancestor of all plastids and, for much of Earth's history, the only source of biogenic oxygen and a major source of fixed carbon and nitrogen. One cyanobacterial clade, subsections IV+V, is characterized by multicellularity and cell differentiation, with many members bearing specialized nitrogen-fixing (or diazotrophic) heterocysts and encysting akinetes [1-3]. Molecular clock estimates of the divergence time of this clade are highly variable, ranging from ∼2,000 Ma (mega-annum) [4-9] to ∼500 Ma [10]. The older estimates are invariably calibrated by putative akinete fossils from Paleoproterozoic-Mesoproterozoic rocks around 2,100-1,400 Ma [3, 11, 12]. However, the interpretation of these fossils as akinetes has been questioned [13], and the next oldest akinete and heterocyst fossils are ∼410 Ma [14]. Thus, the scarcity of reliable heterocystous cyanobacterial fossils significantly hampers our understanding of the evolution of complex multicellularity among cyanobacteria, their role in regulating geochemical cycles in the geological past, and our ability to calibrate cyanobacterial molecular clocks. Here, we report Tonian (∼1,000-720 Ma) filamentous cyanobacteria that are characterized by large cells, binary fission (for filament elongation), hormogonia (for asexual reproduction and dispersal), probable akinetes (for survival in adverse conditions), and by implication, diazotrophic heterocysts. The new fossils provide a minimum age calibration on the divergence of subsections IV+V and place a firm constraint on the evolution of akinetes and heterocysts.


Assuntos
Cianobactérias/classificação , Fósseis , Fixação de Nitrogênio , China , Cianobactérias/citologia , Cianobactérias/fisiologia
19.
Biosci Biotechnol Biochem ; 82(3): 525-531, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29375025

RESUMO

To establish a sensitive bioassay for Nostocean hormogonium induction, we compared the effectiveness of the morpho-differentiation induction on two gelled plates, agar and gellan gum, for anacardic acid C15:1-Δ8 decyl ester (1) (100 nmol/disc). On BG-110 (nitrogen-free) medium-based 0.6 and 0.8% agar plates, Nostoc sp. strain Yaku-1 isolated from a coralloid root of Cycas revoluta in Yakushima Island showed clear morpho-differentiation from filamentous aggregates into hormogonia, and the induced hormogonia dispersed within 24 h; however, similar hormogonium formation was not observed at agar concentrations of 1.0% or higher. Conversely, hormogonium induction was considerably more pronounced on gellan gum plates than those on agar plates through concentrations ranging from 0.6 to 1.6% even after 12 h of incubation, particularly active on the 0.8-1.0% gellan gum plates. Thus, gellan gum plates can achieve clear results within 12 h and are thus highly useful for primary screening for hormogonium-inducing factors (HIFs).


Assuntos
Ágar/farmacologia , Movimento Celular/efeitos dos fármacos , Cianobactérias/citologia , Cianobactérias/efeitos dos fármacos , Polissacarídeos Bacterianos/farmacologia , Bioensaio , Diferenciação Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga
20.
Nat Ecol Evol ; 2(3): 437-440, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29358605

RESUMO

The Ediacara biota (~575-541 million years ago) mark the emergence of large, complex organisms in the palaeontological record, preluding the radiation of modern animal phyla. However, their phylogenetic relationships, even at the domain level, remain controversial. We report the discovery of molecular fossils from organically preserved specimens of Beltanelliformis, demonstrating that they represent large spherical colonies of cyanobacteria. The conservation of molecular remains in organically preserved Ediacaran organisms opens a new path for unravelling the natures of the Ediacara biota.


Assuntos
Evolução Biológica , Cianobactérias/química , Cianobactérias/classificação , Fósseis , Biomarcadores/análise , Cianobactérias/citologia , Cromatografia Gasosa-Espectrometria de Massas , Paleontologia , Federação Russa
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