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1.
mSphere ; 4(3)2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-31043519

RESUMO

Cyanobacteria are prokaryotes capable of oxygenic photosynthesis, and frequently, nitrogen fixation as well. As a result, they contribute substantially to global primary production and nitrogen cycles. Furthermore, the multicellular filamentous cyanobacteria in taxonomic subsections IV and V are developmentally complex, exhibiting an array of differentiated cell types and filaments, including motile hormogonia, making them valuable model organisms for studying development. To investigate the role of sigma factors in the gene regulatory network (GRN) controlling hormogonium development, a combination of genetic, immunological, and time-resolved transcriptomic analyses were conducted in the model filamentous cyanobacterium Nostoc punctiforme, which, unlike other common model cyanobacteria, retains the developmental complexity of field isolates. The results support a model where the hormogonium GRN is driven by a hierarchal sigma factor cascade, with sigJ activating the expression of both sigC and sigF, as well as a substantial portion of additional hormogonium-specific genes, including those driving changes to cellular architecture. In turn, sigC regulates smaller subsets of genes for several processes, plays a dominant role in promoting reductive cell division, and may also both positively and negatively regulate sigJ to reinforce the developmental program and coordinate the timing of gene expression, respectively. In contrast, the sigF regulon is extremely limited. Among genes with characterized roles in hormogonium development, only pilA shows stringent sigF dependence. For sigJ-dependent genes, a putative consensus promoter was also identified, consisting primarily of a highly conserved extended -10 region, here designated a J-Box, which is widely distributed among diverse members of the cyanobacterial lineage.IMPORTANCE Cyanobacteria are integral to global carbon and nitrogen cycles, and their metabolic capacity coupled with their ease of genetic manipulation make them attractive platforms for applications such as biomaterial and biofertilizer production. Achieving these goals will likely require a detailed understanding and precise rewiring of these organisms' GRNs. The complex phenotypic plasticity of filamentous cyanobacteria has also made them valuable models of prokaryotic development. However, current research has been limited by focusing primarily on a handful of model strains which fail to reflect the phenotypes of field counterparts, potentially limiting biotechnological advances and a more comprehensive understanding of developmental complexity. Here, using Nostoc punctiforme, a model filamentous cyanobacterium that retains the developmental range of wild isolates, we define previously unknown definitive roles for a trio of sigma factors during hormogonium development. These findings substantially advance our understanding of cyanobacterial development and gene regulation and could be leveraged for future applications.


Assuntos
Proteínas de Bactérias/genética , Fímbrias Bacterianas/genética , Nostoc/crescimento & desenvolvimento , Nostoc/genética , Fator sigma/genética , Proteínas de Bactérias/metabolismo , Proteínas de Ligação a DNA/genética , Perfilação da Expressão Gênica , Regulação Bacteriana da Expressão Gênica , Regulon , Fator sigma/metabolismo
2.
J Agric Food Chem ; 67(8): 2235-2244, 2019 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-30724068

RESUMO

To explore the regulatory factor of light quality affecting exopolysaccharide (EPS) production, transcriptome analysis of Nostoc flagelliforme cells exposed to red light (R), blue light (B), and mixed light (B/R = 15:7) (BR) with white fluorescent light as control was performed. The differentially expressed genes mainly enriched in carbohydrate metabolism and energy metabolism. Significant enrichment in the oxidation-reduction process and energy metabolism indicated that intracellular redox homeostasis was disrupted. An assay of reactive oxygen species (ROS) and malondialdehyde contents demonstrated light quality induced oxidative stress. To illustrate the relationship between ROS level and EPS accumulation, the effects of the exogenous addition of ROS scavenger N-acetyl cysteine and inducer H2O2 on the oxidation-reduction level and EPS production were compared. The results revealed that light quality regulated EPS biosynthesis via the intracellular ROS level directly other than oxidative stress. Understanding such relationships might provide guidance for efficient EPS production to regulate the intracellular redox level.


Assuntos
Nostoc/metabolismo , Polissacarídeos Bacterianos/biossíntese , Espécies Reativas de Oxigênio/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Meios de Cultura/metabolismo , Peróxido de Hidrogênio/metabolismo , Luz , Nostoc/genética , Nostoc/crescimento & desenvolvimento , Nostoc/efeitos da radiação , Oxirredução , Estresse Oxidativo/efeitos da radiação
3.
J Sci Food Agric ; 99(2): 639-646, 2019 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-29951991

RESUMO

BACKGROUND: Gel-like constructs can be produced using an extrusion-based 3D food printing (3D-FP) technique. Nostoc sphaeroides biomass is a natural gel material. Considering its good nutrition and rheological properties, these algae were chosen in this study as supply material (ink) for 3D-FP. With this gel material, the extrusion-based 3D printing system was set as a model, and the printing behavior was investigated. Furthermore, the 3D-FP mechanisms were explained through low-field nuclear magnetic resonance and rheological measurements. RESULTS: Results indicated that although fresh biomass gel was printable, non-uniformity and instability occurred during printing. Blanched inks showed non-smooth printing behavior, which was associated with a decrease in elasticity and viscosity. Printability was improved by increasing the rehydration time to 24 h when rehydrated powder was used. Increasing the rehydration time increased the water-binding degree. Pre-gelatinized potato starch was added to the mixture at ratios ranging from 1 to 100 g kg-1 . The best printing outcome was observed at 40 g kg-1 potato starch. CONCLUSION: We emphasize that elasticity and viscosity balance is an essential parameter to achieve printability. The strategies adopted in this work provide new insights into the development of personalized food regarding texture and nutritional additive content. © 2018 Society of Chemical Industry.


Assuntos
Nostoc/química , Polissacarídeos/química , Impressão Tridimensional/instrumentação , Biomassa , Elasticidade , Tinta , Nostoc/crescimento & desenvolvimento , Reologia , Viscosidade
4.
PLoS One ; 13(9): e0203898, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30204806

RESUMO

Short and well defined promoters are essential for advancing cyanobacterial biotechnology. The heterocyst of Nostoc sp. is suggested as a microbial cell factory for oxygen sensitive catalysts, such as hydrogenases for hydrogen production, due to its microoxic environment. We identified and predicted promoter elements of possible significance through a consensus strategy using a pool of heterocyst-induced DIF+ promoters known from Anabaena sp. PCC 7120. To test if these conserved promoter elements were crucial for heterocyst-specific expression, promoter-yfp reporter constructs were designed. The characterization was accomplished by replacing, -35 and -10 regions and the upstream element, with well described elements from the trc promoter of Escherichia coli, which is also functional in Nostoc sp. From the in vivo spatial fluorescence of the different promoter-yfp reporters in Nostoc punctiforme ATCC 29133, we concluded that both the consensus -35 and extended -10 regions were important for heterocyst-specific expression. Further that the promoter strength could be improved by the addition of an upstream element. We designed a short synthetic promoter of 48 nucleotides, PsynDIF, including a consensus DIF1 sequence, a 17 base pair stretch of random nucleotides and an extended consensus -10 region, and thus generated the shortest promoter for heterocyst-specific expression to date.


Assuntos
Cianobactérias/genética , Genes Sintéticos , Regiões Promotoras Genéticas , Anabaena/genética , Proteínas de Bactérias/genética , Biotecnologia , Sequência Consenso , Cianobactérias/crescimento & desenvolvimento , Cianobactérias/metabolismo , DNA Bacteriano/genética , Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica , Genes Bacterianos , Genes Reporter , Proteínas Luminescentes/genética , Fixação de Nitrogênio/genética , Nostoc/genética , Nostoc/crescimento & desenvolvimento , Nostoc/metabolismo
5.
FEMS Microbiol Ecol ; 94(1)2018 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-29228342

RESUMO

Germination of akinetes of filamentous heterocyst-forming cyanobacteria of the order Nostocales is an essential process that ensures survival and recolonization after long periods of unfavorable conditions, as desiccation, cold and low light. We studied the morphological, physiological and metabolic changes that occur during germination of akinetes in two model species of cell differentiation, Anabaena variabilis ATCC 29413 and Nostoc punctiforme ATCC 29133, which live in different habitats. We characterized the akinete envelopes and showed their similarity to envelopes of N2-fixing heterocysts. Akinete germination started inside the envelopes and was dependent on light intensity but independent of nitrogen supply. During the germination of A. variabilis akinetes, cell division and heterocyst differentiation were highly accelerated. The energy for cell division was initially supplied by respiration of glycogen and subsequently by photosynthesis. By contrast, during germination of N. punctiforme akinetes, cell division and heterocyst differentiation were slow. During the initial 15-20 h, N. punctiforme akinetes increased in volume and some burst. Only then did intact akinetes start to divide and fully germinate, possibly fueled by nutrients released from dead akinetes. The different strategies used by these different cyanobacteria allow successful germination of dormant cells and recolonization under favorable conditions.


Assuntos
Anabaena variabilis/crescimento & desenvolvimento , Anabaena variabilis/metabolismo , Nostoc/crescimento & desenvolvimento , Nostoc/metabolismo , Esporos Bacterianos/crescimento & desenvolvimento , Proteínas de Bactérias/genética , Diferenciação Celular/fisiologia , Divisão Celular/fisiologia , Membrana Celular/fisiologia , Glicogênio/metabolismo , Luz , Nitrogênio/metabolismo , Fotossíntese/fisiologia , Esporos Bacterianos/fisiologia
6.
Appl Environ Microbiol ; 83(23)2017 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-28939609

RESUMO

Terrestrial symbiotic cyanobacteria of the genus Nostoc exhibit a large potential for the production of bioactive natural products of the nonribosomal peptide, polyketide, and ribosomal peptide classes, and yet most of the biosynthetic gene clusters are silent under conventional cultivation conditions. In the present study, we utilized a high-density cultivation approach recently developed for phototrophic bacteria to rapidly generate biomass of the filamentous bacteria up to a density of 400 g (wet weight)/liter. Unexpectedly, integrated transcriptional and metabolomics studies uncovered a major reprogramming of the secondary metabolome of two Nostoc strains at high culture density and a governing effect of extracellular signals in this process. The holistic approach enabled capturing and structural elucidation of novel variants of anabaenopeptin, including one congener with potent allelopathic activity against a strain isolated from the same habitat. The study provides a snapshot on the role of cell-type-specific expression for the formation of natural products in cyanobacteria.IMPORTANCE Terrestrial filamentous cyanobacteria are a largely untapped source of small-molecule natural products. Exploitation of the phototrophic organisms is hampered by their slow growth and the requirement of photobioreactors. The present study not only demonstrates the suitability of a recently developed two-tier vessel cultivation approach for the rapid generation of biomass of Nostoc strains but also demonstrates a pronounced upregulation of high value natural products at ultrahigh culture densities. The study provides new guidelines for high-throughput screening and exploitation of small-molecule natural products and can facilitate the discovery new bioactive products from terrestrial cyanobacteria.


Assuntos
Metaboloma , Nostoc/metabolismo , Produtos Biológicos , Família Multigênica , Nostoc/crescimento & desenvolvimento
7.
Appl Environ Microbiol ; 83(13)2017 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-28455341

RESUMO

To investigate the function of 2-methylhopanoids in modern cyanobacteria, the hpnP gene coding for the radical S-adenosyl methionine (SAM) methylase protein that acts on the C-2 position of hopanoids was deleted from the filamentous cyanobacterium Nostoc punctiforme ATCC 29133S. The resulting ΔhpnP mutant lacked all 2-methylhopanoids but was found to produce much higher levels of two bacteriohopanepentol isomers than the wild type. Growth rates of the ΔhpnP mutant cultures were not significantly different from those of the wild type under standard growth conditions. Akinete formation was also not impeded by the absence of 2-methylhopanoids. The relative abundances of the different hopanoid structures in akinete-dominated cultures of the wild-type and ΔhpnP mutant strains were similar to those of vegetative cell-dominated cultures. However, the ΔhpnP mutant was found to have decreased growth rates under both pH and osmotic stress, confirming a role for 2-methylhopanoids in stress tolerance. Evidence of elevated photosystem II yield and NAD(P)H-dependent oxidoreductase activity in the ΔhpnP mutant under stress conditions, compared to the wild type, suggested that the absence of 2-methylhopanoids increases cellular metabolic rates under stress conditions.IMPORTANCE As the first group of organisms to develop oxygenic photosynthesis, Cyanobacteria are central to the evolutionary history of life on Earth and the subsequent oxygenation of the atmosphere. To investigate the origin of cyanobacteria and the emergence of oxygenic photosynthesis, geobiologists use biomarkers, the remnants of lipids produced by different organisms that are found in geologic sediments. 2-Methylhopanes have been considered indicative of cyanobacteria in some environmental settings, with the parent lipids 2-methylhopanoids being present in many contemporary cyanobacteria. We have created a Nostoc punctiforme ΔhpnP mutant strain that does not produce 2-methylhopanoids to assess the influence of 2-methylhopanoids on stress tolerance. Increased metabolic activity in the mutant under stress indicates compensatory alterations in metabolism in the absence of 2-methylhopanoids.


Assuntos
Nostoc/metabolismo , Triterpenos/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Concentração de Íons de Hidrogênio , Isomerismo , Metilação , Nostoc/química , Nostoc/genética , Nostoc/crescimento & desenvolvimento , Osmose , Triterpenos/química
8.
J Bacteriol ; 199(9)2017 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-28242721

RESUMO

Most species of filamentous cyanobacteria are capable of gliding motility, likely via a conserved type IV pilus-like system that may also secrete a motility-associated polysaccharide. In a subset of these organisms, motility is achieved only after the transient differentiation of hormogonia, which are specialized filaments that enter a nongrowth state dedicated to motility. Despite the fundamental importance of hormogonia to the life cycles of many filamentous cyanobacteria, the molecular regulation of hormogonium development is largely undefined. To systematically identify genes essential for hormogonium development and motility in the model heterocyst-forming filamentous cyanobacterium Nostoc punctiforme, a forward genetic screen was employed. The first gene identified using this screen, designated ogtA, encodes a putative O-linked ß-N-acetylglucosamine transferase (OGT). The deletion of ogtA abolished motility, while ectopic expression of ogtA induced hormogonium development even under hormogonium-repressing conditions. Transcription of ogtA is rapidly upregulated (1 h) following hormogonium induction, and an OgtA-GFPuv fusion protein localized to the cytoplasm. In developing hormogonia, accumulation of PilA but not HmpD is dependent on ogtA Reverse transcription-quantitative PCR (RT-qPCR) analysis indicated equivalent levels of pilA transcript in the wild-type and ΔogtA mutant strains, while a reporter construct consisting of the intergenic region in the 5' direction of pilA fused to gfp produced lower levels of fluorescence in the ΔogtA mutant strain than in the wild type. The production of hormogonium polysaccharide in the ΔogtA mutant strain is reduced compared to that in the wild type but comparable to that in a pilA deletion strain. Collectively, these results imply that O-GlcNAc protein modification regulates the accumulation of PilA via a posttranscriptional mechanism in developing hormogonia.IMPORTANCE Filamentous cyanobacteria are among the most developmentally complex prokaryotes. Species such as Nostoc punctiforme develop an array of cell types, including nitrogen-fixing heterocysts, spore-like akinetes, and motile hormogonia, that function in dispersal as well as the establishment of nitrogen-fixing symbioses with plants and fungi. These symbioses are major contributors to global nitrogen fixation. Despite the fundamental importance of hormogonia to the life cycle of filamentous cyanobacteria and the establishment of symbioses, the molecular regulation of hormogonium development is largely undefined. We employed a genetic screen to identify genes essential for hormogonium development and motility in Nostoc punctiforme The first gene identified using this screen encodes a eukaryotic-like O-linked ß-N-acetylglucosamine transferase that is required for accumulation of PilA in hormogonia.


Assuntos
N-Acetilglucosaminiltransferases/metabolismo , Nostoc/enzimologia , Nostoc/crescimento & desenvolvimento , Proteínas de Bactérias/genética , Fímbrias Bacterianas/genética , Fímbrias Bacterianas/fisiologia , Perfilação da Expressão Gênica , Regulação Bacteriana da Expressão Gênica , Movimento , Mutação , N-Acetilglucosaminiltransferases/genética , Nostoc/genética , Simbiose
9.
Appl Environ Microbiol ; 82(21): 6344-6356, 2016 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-27542935

RESUMO

In bacteria, limited phosphate availability promotes the synthesis of active uptake systems, such as the Pst phosphate transport system. To understand the mechanisms that facilitate phosphate accumulation in the cyanobacterium Nostoc punctiforme, phosphate transport systems were identified, revealing a redundancy of Pst phosphate uptake systems that exists across three distinct operons. Four separate PstB system components were identified. pstB1 was determined to be a suitable target for creating phenotypic mutations that could result in the accumulation of excessive levels of phosphate through its overexpression or in a reduction of the capacity to accumulate phosphate through its deletion. Using quantitative real-time PCR (qPCR), it was determined that pstB1 mRNA levels increased significantly over 64 h in cells cultured in 0 mM added phosphate and decreased significantly in cells exposed to high (12.8 mM) phosphate concentrations compared to the level in cells cultured under normal (0.8 mM) conditions. Possible compensation for the loss of PstB1 was observed when pstB2, pstB3, and pstB4 mRNA levels increased, particularly in cells starved of phosphate. The overexpression of pstB1 increased phosphate uptake by N. punctiforme and was shown to functionally complement the loss of PstB in E. coli PstB knockout (PstB-) mutants. The knockout of pstB1 in N. punctiforme did not have a significant effect on cellular phosphate accumulation or growth for the most part, which is attributed to the compensation for the loss of PstB1 by alterations in the pstB2, pstB3, and pstB4 mRNA levels. This study provides novel in vivo evidence that PstB1 plays a functional role in phosphate uptake in N. punctiforme IMPORTANCE: Cyanobacteria have been evolving over 3.5 billion years and have become highly adept at growing under limiting nutrient levels. Phosphate is crucial for the survival and prosperity of all organisms. In bacteria, limited phosphate availability promotes the synthesis of active uptake systems. The Pst phosphate transport system is one such system, responsible for the internalization of phosphate when cells are in phosphate-limited environments. Our investigations reveal the presence of multiple Pst phosphate uptake systems that exist across three distinct operons in Nostoc punctiforme and functionally characterize the role of the gene product PstB1 as being crucial for the maintenance of phosphate accumulation. We demonstrate that the genes pstB2, pstB3, and pstB4 show alterations in expression to compensate for the deletion of pstB1 The overall outcomes of this work provide insights as to the complex transport mechanisms that exist in cyanobacteria like N. punctiforme, allowing them to thrive in low-phosphate environments.


Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Adenosina Trifosfatases/metabolismo , Proteínas de Bactérias/metabolismo , Nostoc/metabolismo , Fosfatos/metabolismo , Transportadores de Cassetes de Ligação de ATP/genética , Adenosina Trifosfatases/genética , Proteínas de Bactérias/genética , Escherichia coli/genética , Técnicas de Inativação de Genes , Mutação , Nostoc/efeitos dos fármacos , Nostoc/genética , Nostoc/crescimento & desenvolvimento , Fosfatos/deficiência , Fosfatos/farmacologia , RNA Mensageiro , Reação em Cadeia da Polimerase em Tempo Real
10.
Biochim Biophys Acta ; 1857(6): 715-22, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26896589

RESUMO

Organisms inhabiting biological soil crusts (BSCs) are able to cope with extreme environmental conditions including daily hydration/dehydration cycles, high irradiance and extreme temperatures. The photosynthetic machinery, potentially the main source of damaging reactive oxygen species during cessation of CO(2) fixation in desiccating cells, must be protected to avoid sustained photodamage. We compared certain photosynthetic parameters and the response to excess light of BCS-inhabiting, desiccation-tolerant cyanobacteria Leptolyngbya ohadii and Nostoc reinholdii with those observed in the "model" organisms Nostoc sp. PCC 7120, able to resurrect after mild desiccation, and Synechococcus elongatus PCC 7942 and Synechocystis sp. PCC 6803 that are unable to recover from dehydration. Desiccation-tolerant strains exhibited a transient decline in the photosynthetic rate at light intensities corresponding to the inflection point in the PI curve relating the O(2) evolution rate to light intensity. They also exhibited a faster and larger loss of variable fluorescence and profoundly faster Q(A)(-) re-oxidation rates after exposure to high illumination. Finally, a smaller difference was found in the temperature of maximal thermoluminescence signal in the absence or presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) than observed in "model" cyanobacteria. These parameters indicate specific functional differences of photosystem II (PSII) between desiccation tolerant and sensitive cyanobacteria. We propose that exposure to excess irradiation activates a non-radiative electron recombination route inside PSII that minimizes formation of damaging singlet oxygen in the desiccation-tolerant cyanobacteria and thereby reduces photodamage.


Assuntos
Cianobactérias/crescimento & desenvolvimento , Cianobactérias/metabolismo , Dessecação/métodos , Complexo de Proteína do Fotossistema II/metabolismo , Cianobactérias/classificação , Cinética , Luz , Nostoc/crescimento & desenvolvimento , Nostoc/metabolismo , Oxirredução/efeitos da radiação , Oxigênio/metabolismo , Fotossíntese/efeitos da radiação , Especificidade da Espécie , Synechococcus/crescimento & desenvolvimento , Synechococcus/metabolismo , Synechocystis/crescimento & desenvolvimento , Synechocystis/metabolismo , Temperatura Ambiente , Fatores de Tempo
11.
J Biotechnol ; 223: 1-5, 2016 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-26902690

RESUMO

Two cyanobacterial strains, Synechocystis sp. PCC 6803 and Nostoc punctiforme ATCC 29133 were immobilized within magnesium phosphate based cements, showing a viability and activity for at least 4 weeks. These biohybrids are considered as an alternative photobioreactor material for bioremediation or an improved yield of biotechnologically relevant molecules.


Assuntos
Cianobactérias/crescimento & desenvolvimento , Fotobiorreatores/microbiologia , Técnicas de Cultura de Células , Cerâmica , Nostoc/crescimento & desenvolvimento , Synechocystis/crescimento & desenvolvimento
12.
J Microbiol Biotechnol ; 26(4): 648-58, 2016 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-26699749

RESUMO

Preservation of fresh algae plays an important role in algae seed subculture and aquaculture. The determination and examination of the changes of cell viability, composition, and bacterial species during storage would help to take suitable preservation methods to prolong the preservation time of fresh algae. Nostoc flagelliforme is a kind of edible cyanobacterium with important herbal and dietary values. This article investigated the changes of bacterial species and biochemical characteristics of fresh N. flagelliforme concentrate during natural storage. It was found that the viability of cells decreased along with the storage time. Fourteen bacteria strains in the algae concentrate were identified by PCR-DGGE and were grouped into four phyla, including Cyanobacteria, Firmicutes, Proteobacteria, and Bacteroidetes. Among them, Enterococcus viikkiensis may be a concern in the preservation. Eleven volatile organic compounds were identified from N. flagelliforme cells, in which geosmin could be treated as an indicator of the freshness of N. flagelliforme. The occurrence of indole compound may be an indicator of the degradation of cells.


Assuntos
Viabilidade Microbiana , Nostoc/classificação , Nostoc/fisiologia , Preservação Biológica , Bacteroidetes/genética , Bacteroidetes/isolamento & purificação , Meios de Cultura , Cianobactérias/genética , Cianobactérias/isolamento & purificação , Firmicutes/genética , Firmicutes/isolamento & purificação , Indóis/análise , Naftóis/análise , Nostoc/química , Nostoc/crescimento & desenvolvimento , Filogenia , Reação em Cadeia da Polimerase , Proteobactérias/genética , Proteobactérias/isolamento & purificação , Compostos Orgânicos Voláteis
13.
Arch Microbiol ; 198(2): 137-47, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26576759

RESUMO

Nostoc punctiforme is a filamentous cyanobacterium which forms nitrogen-fixing symbioses with several different plants and fungi. Establishment of these symbioses requires the formation of motile hormogonium filaments. Once infected, the plant partner is thought to supply a hormogonium-repressing factor (HRF) to maintain the cyanobacteria in a vegetative, nitrogen-fixing state. Evidence implies that sucrose may serve as a HRF. Here, we tested the effects of sucralose, a non-metabolizable sucrose analog, on hormogonium differentiation. Sucralose inhibited hormogonium differentiation at a concentration approximately one-tenth that of sucrose. This result implies that: (1) sucrose, not a sucrose catabolite, is perceived by the cell and (2) inhibition is not due to a more general osmolarity-dependent effect. Additionally, both sucrose and sucralose induced the accrual of a polysaccharide sheath which bound specifically to the lectin ConA, indicating the presence of α-D-mannose and/or α-D-glucose. A ConA-specific polysaccharide was also found to be expressed in N. punctiforme colonies from tissue sections of the symbiotically grown hornwort Anthoceros punctatus. These findings imply that plant-derived sucrose or sucrose analogs may have multiple effects on N. punctiforme, including both repression of hormogonia and the induction of a polysaccharide sheath that may be essential to establish and maintain the symbiotic state.


Assuntos
Nostoc/efeitos dos fármacos , Sacarose/análogos & derivados , Simbiose , Magnoliopsida/microbiologia , Nostoc/crescimento & desenvolvimento , Polissacarídeos Bacterianos/metabolismo , Sacarose/farmacologia
14.
Mol Microbiol ; 98(6): 1021-36, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26331359

RESUMO

In filamentous cyanobacteria, the mechanism of gliding motility is undefined but posited to be driven by a polysaccharide secretion system known as the junctional pore complex (JPC). Recent evidence implies that the JPC is a modified type IV pilus-like structure encoded for in part by genes in the hps locus. To test this hypothesis, we conducted genetic, cytological and comparative genomics studies on hps and pil genes in Nostoc punctiforme, a species in which motility is restricted to transiently differentiated filaments called hormogonia. Inactivation of most hps and pil genes abolished motility and abolished or drastically reduced secretion of hormogonium polysaccharide, and the subcellular localization of several Pil proteins in motile hormogonia corresponds to the site of the junctional pore complex. The non-motile ΔhpsE-G strain, which lacks three glycosyltransferases that synthesize hormogonium polysaccharide, could be complemented to motility by the addition of medium conditioned by wild-type hormogonia. Based on this result, we speculate that secretion of hormogonium polysaccharide facilitates but does not provide the motive force for gliding. Both the Hps and Pil homologs characterized in this study are almost universally conserved among filamentous cyanobacteria, with the Hps homologs rarely found in unicellular strains. These results support the theory that Hps and Pil proteins compose the JPC, a type IV pilus-like nanomotor that drives motility and polysaccharide secretion in filamentous cyanobacteria.


Assuntos
Proteínas de Fímbrias/metabolismo , Fímbrias Bacterianas/fisiologia , Nostoc/fisiologia , Polissacarídeos Bacterianos/metabolismo , Proteínas de Bactérias/metabolismo , Membrana Celular/metabolismo , Meios de Cultivo Condicionados , Proteínas de Fímbrias/genética , Fímbrias Bacterianas/genética , Regulação Bacteriana da Expressão Gênica , Genômica , Glicosiltransferases/metabolismo , Movimento , Nostoc/genética , Nostoc/crescimento & desenvolvimento , Nostoc/ultraestrutura
15.
J Biotechnol ; 215: 35-43, 2015 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-26325196

RESUMO

Nitrogenase based hydrogen production was examined in a ΔhupW strain of the filamentous heterocystous cyanobacterium Nostoc PCC 7120, i.e., cells lacking the last step in the maturation system of the large subunit of the uptake hydrogenase and as a consequence with a non-functional uptake hydrogenase. The cells were grown in a developed flat panel photobioreactor system with 3.0L culture volume either aerobically (air) or anaerobically (Ar or 80% N2/20% Ar) and illuminated with a mixture of red and white LED. Aerobic growth of the ΔhupW strain of Nostoc PCC 7120 at 44µmolar photons m(-2)s(-1) PAR gave the highest hydrogen production of 0.7mL H2 L(-1)h(-1), 0.53mmol H2 mg chlorophyll a(-1)h(-1), and a light energy conversion efficiency of 1.2%. Anaerobic growth using 100% argon showed a maximal hydrogen production of 1.7mLL(-1)h(-1), 0.85mmol per mg chlorophyll a(-1) h(-1), and a light energy conversion efficiency of 2.7%. Altering between argon/N2 (20/80) and 100% argon phases resulted in a maximal hydrogen production at hour 128 (100% argon phase) with 6.2mL H2L(-1)h(-1), 0.71mL H2 mg chlorophyll a(-1)h(-1), and a light energy efficiency conversion of 4.0%. The highest buildup of hydrogen gas observed was 6.89% H2 (100% argon phase) of the total photobioreactor system with a maximal production of 4.85mL H2 L(-1)h(-1). The present study clearly demonstrates the potential to use purpose design cyanobacteria in developed flat panel photobioreactor systems for the direct production of the solar fuel hydrogen. Further improvements in the strain used, environmental conditions employed, and growth, production and collection systems used, are needed before a sustainable and economical cyanobacterial based hydrogen production can be realized.


Assuntos
Hidrogênio/metabolismo , Nostoc/metabolismo , Fotobiorreatores , Argônio/administração & dosagem , Clorofila , Clorofila A , Engenharia Genética , Iluminação , Nitrogênio/administração & dosagem , Nitrogenase , Nostoc/genética , Nostoc/crescimento & desenvolvimento , Oxirredutases , Oxigênio/administração & dosagem
16.
Appl Biochem Biotechnol ; 176(8): 2279-89, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26100389

RESUMO

A study was conducted to investigate the effect of light intensity (21, 42, and 63 µmol photons m(-2) s(-1)) and photoperiod (8:16, 12:12, and 16:8 h light/dark) on the biomass production and its biochemical composition (total carotenoids, chlorophyll a, phycoerythrin (PE), phycocyanin (PC) and allophycocyanin (APC), total protein, and carbohydrates) of a local isolate of Nostoc calcicola. The results revealed that N. calcicola prefers dim light; however, the most of the levels of light intensity and photoperiod investigated did not have a significant impact on biomass production. Increasing light intensity biomass content of chlorophyll a, PE, PC, APC, and total protein decreased, while total carotenoids and carbohydrate increased. The same behavior was observed also when light duration (photoperiod) increased. The interaction effect of increasing light intensity and photoperiod resulted in an increase of carbohydrate and total carotenoids, and to the decrease of chlorophyll a, PE, PC, APC, and total protein content. The results indicate that varying the light regime, it is capable to manipulate the biochemical composition of the local isolate of N. calcicola, producing either valuable phycobiliproteins or proteins under low light intensity and shorter photoperiods, or producing carbohydrates and carotenoids under higher light intensities and longer photoperiods.


Assuntos
Luz , Nostoc/crescimento & desenvolvimento , Nostoc/metabolismo , Fotoperíodo , Proteínas de Bactérias/metabolismo , Biomassa , Carboidratos/química , Carotenoides/metabolismo , Clorofila/metabolismo , Nostoc/isolamento & purificação , Nostoc/efeitos da radiação , Ficocianina/metabolismo , Ficoeritrina/metabolismo
17.
Appl Biochem Biotechnol ; 176(7): 1950-63, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26041059

RESUMO

Bioflocculant exopolysaccharide (EPS) production by 40 cyanobacterial strains during their photoautotrophic growth was investigated. Highest levels of EPS were produced by Nostoc sp. BTA97 and Anabaena sp. BTA990. EPS production was maximum during stationary growth phase, when nitrogenase activity was very low. Maximum EPS production occurred at pH 8.0 in the absence of any combined nitrogen source. The cyanobacterial EPS consisted of soluble protein and polysaccharide that included substantial amounts of neutral sugars and uronic acid. The EPS isolated from Anabaena sp. BTA990 and Nostoc sp. BTA97 demonstrated high flocculation capacity. There was a positive correlation between uronic acid content and flocculation activity. The flocculant bound a cationic dye, Alcian Blue, indicating it to be polyanionic. The 16S rRNA gene sequences for Nostoc sp. BTA97 and Anabaena sp. BTA990 were deposited at NCBI GenBank, and accession numbers were obtained as KJ830951 and KJ830948, respectively. The results of these experiments indicate that strains Anabaena sp. BTA990 and Nostoc sp. BTA97 are good candidates for the commercial production of EPS and might be utilized in industrial applications as an alternative to synthetic and abiotic flocculants.


Assuntos
Anabaena/crescimento & desenvolvimento , Anabaena/metabolismo , Nostoc/crescimento & desenvolvimento , Nostoc/metabolismo , Polissacarídeos/biossíntese , Anabaena/química , Anabaena/citologia , Técnicas de Cultura , Espaço Extracelular/efeitos dos fármacos , Espaço Extracelular/metabolismo , Floculação , Concentração de Íons de Hidrogênio , Cinética , Dados de Sequência Molecular , Nitratos/farmacologia , Nostoc/química , Nostoc/citologia , Filogenia , RNA Ribossômico 16S/genética , Ácidos Urônicos/metabolismo
18.
Mar Drugs ; 13(4): 2124-40, 2015 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-25871291

RESUMO

Cyanobacteria are photosynthetic prokaryotes found in a range of environments. They are infamous for the production of toxins, as well as bioactive compounds, which exhibit anticancer, antimicrobial and protease inhibition activities. Cyanobacteria produce a broad range of antifungals belonging to structural classes, such as peptides, polyketides and alkaloids. Here, we tested cyanobacteria from a wide variety of environments for antifungal activity. The potent antifungal macrolide scytophycin was detected in Anabaena sp. HAN21/1, Anabaena cf. cylindrica PH133, Nostoc sp. HAN11/1 and Scytonema sp. HAN3/2. To our knowledge, this is the first description of Anabaena strains that produce scytophycins. We detected antifungal glycolipopeptide hassallidin production in Anabaena spp. BIR JV1 and HAN7/1 and in Nostoc spp. 6sf Calc and CENA 219. These strains were isolated from brackish and freshwater samples collected in Brazil, the Czech Republic and Finland. In addition, three cyanobacterial strains, Fischerella sp. CENA 298, Scytonema hofmanni PCC 7110 and Nostoc sp. N107.3, produced unidentified antifungal compounds that warrant further characterization. Interestingly, all of the strains shown to produce antifungal compounds in this study belong to Nostocales or Stigonematales cyanobacterial orders.


Assuntos
Antifúngicos/isolamento & purificação , Aspergillus flavus/efeitos dos fármacos , Candida albicans/efeitos dos fármacos , Cianobactérias/química , Descoberta de Drogas , Anabaena/química , Anabaena/classificação , Anabaena/crescimento & desenvolvimento , Anabaena/isolamento & purificação , Antifúngicos/química , Antifúngicos/farmacologia , Aspergillus flavus/crescimento & desenvolvimento , Brasil , Candida albicans/crescimento & desenvolvimento , Cianobactérias/classificação , Cianobactérias/crescimento & desenvolvimento , Cianobactérias/isolamento & purificação , República Tcheca , Finlândia , Água Doce/microbiologia , Glicolipídeos/química , Glicolipídeos/isolamento & purificação , Glicolipídeos/farmacologia , Lipopeptídeos/química , Lipopeptídeos/isolamento & purificação , Lipopeptídeos/farmacologia , Estrutura Molecular , Tipagem Molecular , Nostoc/química , Nostoc/classificação , Nostoc/crescimento & desenvolvimento , Nostoc/isolamento & purificação , Peptídeos Cíclicos/química , Peptídeos Cíclicos/isolamento & purificação , Peptídeos Cíclicos/farmacologia , Filogenia , Piranos/química , Piranos/isolamento & purificação , Piranos/farmacologia , Águas Salinas , Especificidade da Espécie
19.
Biotechnol Lett ; 37(8): 1663-9, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25864176

RESUMO

OBJECTIVES: To assess the effects of light intensity and quality on the growth and phycobiliproteins (PBP) accumulation in Nostoc sphaeroides Kützing (N. sphaeroides). RESULTS: Dry weights, dry matter, protein, chlorophyll and PBP contents were higher under 90 µmol m(-2) s(-1) than under other intensities (both higher and lower). Phycocyanin and allophycocyanin increased with light intensity while phycoerythrin decreased. Fresh weights, protein and PBP contents increased at the highest rates under blue light. Red light resulted in higher values of dry matter, phycocyanin and chlorophyll a. CONCLUSION: White light at 90 µmol m(-2) s(-1) or blue light 30 µmol m(-2) s(-1) were optimal for the growth and phycobiliprotein accumulation in N. sphaeroides.


Assuntos
Luz , Nostoc/química , Nostoc/efeitos da radiação , Ficobiliproteínas/análise , Biomassa , Cor , Nostoc/crescimento & desenvolvimento
20.
Protoplasma ; 252(6): 1551-61, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25772678

RESUMO

The adaptability of cyanobacteria in diverse habitats is an important factor to withstand harsh conditions. In the present investigation, the impacts of photosynthetically active radiation (PAR; 400-700 nm), ultraviolet-B (UV-B; 280-315 nm), and PAR + UV-B radiations on two cyanobacteria viz., Nostoc sp. HKAR-2 and Nostoc sp. HKAR-11 inhabiting diverse habitats such as hot springs and rice fields, respectively, were studied. Cell viability was about 14 % in Nostoc sp. HKAR-2 and <10 % in Nostoc sp. HKAR-11 after 48 h of UV-B exposure. PAR had negligible negative impact on the survival of both cyanobacteria. The continuous exposure of UV-B and PAR + UV-B showed rapid uncoupling, bleaching, fragmentation, and degradation in both phycocyanin (C-PC) and phycoerythrin (C-PE) subunits of phycobiliproteins (PBPs). Remarkable bleaching effect of C-PE and C-PC was not only observed with UV-B or PAR + UV-B radiation, but longer period (24-48 h) of exposure with PAR alone also showed noticeable negative impact. The C-PE and C-PC subunits of the rice field isolate Nostoc sp. HKAR-11 were severely damaged in comparison to the hot spring isolate Nostoc sp. HKAR-2 with rapid wavelength shifting toward shorter wavelengths denoting the bleaching of both the accessory light harvesting pigments. The results indicate that PBPs of the hot spring isolate Nostoc sp. HKAR-2 were more stable under various light regimes in comparison to the rice field isolate Nostoc sp. HKAR-11 that could serve as a good source of valuable pigments to be used in various biomedical and biotechnological applications.


Assuntos
Ecossistema , Nostoc/efeitos da radiação , Fotoperíodo , Fotossíntese/efeitos da radiação , Ficobiliproteínas/metabolismo , Ficobilissomas/efeitos da radiação , Raios Ultravioleta , Fontes Termais/microbiologia , Viabilidade Microbiana/efeitos da radiação , Nostoc/classificação , Nostoc/crescimento & desenvolvimento , Nostoc/metabolismo , Ficobilissomas/metabolismo , Ficocianina/metabolismo , Ficoeritrina/metabolismo , Desnaturação Proteica , Estabilidade Proteica , Microbiologia do Solo , Espectrometria de Fluorescência , Fatores de Tempo , Microbiologia da Água
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