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1.
Antibiotics (Basel) ; 12(7)2023 Jun 28.
Artículo en Inglés | MEDLINE | ID: mdl-37508210

RESUMEN

BACKGROUND: Massive fruit losses are caused by microbial pathogens of unknown identities. Therefore, ecofriendly biocontrol measures are well sought after, and biogenic silver nanoparticles are plausible candidates. Here we investigate the antimicrobial effect of three different sized AgNPs samples on those pathogens. METHODOLOGY: Identities of three local pathogenic bacteria were investigated using molecular methods. Three different-sized samples of silver nanoparticles were bio-synthesized in the external solution of a cyanobacterial culture, characterized, and used in antimicrobial bioassay. RESULTS: The pathogens were identified as Erwinia pyrifoliae, Staphylococcus warneri, and Xanthomonas citri. UV-vis. and FTIR spectroscopy confirmed the biosynthesis of AgNPs. and their three different sizes were confirmed using Scanning electron microscopy. Growth of bacterial pathogens was inhibited by all three samples of AgNPs, but the largest inhibition zone was for the smallest sized AgNPs against Staphylococcus warneri (1.7 cm). DISCUSSION: The identity of the pathogens infecting different local fruits is reported for the first time. They belong to different bacterial lineages. The fact that biogenic AAgNPs were effective against all of them shows their broad-spectrum of antibacterial effect. Customized biosynthesis was successful in yielding different-sized AgNPs. The smaller the AgNPs, the stronger the antimicrobial impact. CONCLUSION: Local bacterial species infecting fruits are diverse. Customized biogenic AgNPs are effective broad-spectrum biocontrol agents against bacterial pathogens of local fruits and thereby help maintain food security and environmental sustainability.

2.
Micron ; 44: 419-32, 2013 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-23098642

RESUMEN

The prokaryote Corynebacterium matruchotii produces calcium phosphate (bone salt) and may serve as a convenient model for examining individual factors relevant to vertebrate calcification. A factor of current clinical uncertainty is silicon. To investigate its possible role in biomineralisation advanced optical (digital deconvolution and 3D fluorescent image rendering) and electron microscopy (EDX microanalysis and elemental mapping) were applied to calcifying microbial colonies grown in graded Si concentrations (0-60mM). Cell viability was confirmed throughout by TO-PRO-3-iodide and SYTO-9 nucleic acid staining. It was observed that calcium accumulated in dense intracellular microspherical objects (types i-iii) as nanoparticles (5 nm, type i), nanospheres (30-50 nm, type ii) and filamentous clusters (0.1-0.5 µm, type iii), with a regular transitory Si content evident. With bacterial colony development (7-28 days) the P content increased from 5 to 60%, while Si was displaced from 60 to 5%, distinguishing the phenomenon from random contamination, and with a significant relationship (p<0.001) found between calcified object number and Si supplementation (optimum 0.01mM). The Si-containing, intracellular calcified objects (also positive for Mg and negative with Lysensor blue DND-167 for acidocalcisomes) were extruded naturally in bubble-like chains to complete the cycle by coating the cell surface with discrete mineral particles. These could be harvested by lysis, French press and density fractionation when Si was confirmed in a proportion. It was concluded that the unexplained orthopaedic activity of Si may derive from its special property to facilitate calcium phosphorylation in biological systems, thereby recapitulating an ancient and conserved bacterial cycle of calcification via silicification.


Asunto(s)
Fosfatos de Calcio/química , Fosfatos de Calcio/metabolismo , Corynebacterium/metabolismo , Silicio/química , Calcificación Fisiológica , Nanopartículas Calcificantes/química , Microanálisis por Sonda Electrónica , Microscopía Electrónica , Microscopía Electrónica de Rastreo , Microscopía Fluorescente
3.
Mol Membr Biol ; 30(2): 114-28, 2013 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-23256604

RESUMEN

Nucleosides play key roles in biology as precursors for salvage pathways of nucleotide synthesis. Prokaryotes import nucleosides across the cytoplasmic membrane by proton- or sodium-driven transporters belonging to the Concentrative Nucleoside Transporter (CNT) family or the Nucleoside:H(+) Symporter (NHS) family of the Major Facilitator Superfamily. The high resolution structure of a CNT from Vibrio cholerae has recently been determined, but no similar structural information is available for the NHS family. To gain a better understanding of the molecular mechanism of nucleoside transport, in the present study the structures of two conformations of the archetypical NHS transporter NupG from Escherichia coli were modelled on the inward- and outward-facing conformations of the lactose transporter LacY from E. coli, a member of the Oligosaccharide:H(+) Symporter (OHS) family. Sequence alignment of these distantly related proteins (∼ 10% sequence identity), was facilitated by comparison of the patterns of residue conservation within the NHS and OHS families. Despite the low sequence similarity, the accessibilities of endogenous and introduced cysteine residues to thiol reagents were found to be consistent with the predictions of the models, supporting their validity. For example C358, located within the predicted nucleoside binding site, was shown to be responsible for the sensitivity of NupG to inhibition by p-chloromercuribenzene sulphonate. Functional analysis of mutants in residues predicted by the models to be involved in the translocation mechanism, including Q261, E264 and N228, supported the hypothesis that they play important roles, and suggested that the transport mechanisms of NupG and LacY, while different, share common features.


Asunto(s)
Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/metabolismo , Proteínas de Transporte de Membrana/química , Proteínas de Transporte de Membrana/metabolismo , Proteínas de Transporte de Nucleósidos/química , Proteínas de Transporte de Nucleósidos/metabolismo , Nucleósidos/química , Nucleósidos/metabolismo , Secuencia de Aminoácidos , Sitios de Unión , Transporte Biológico , Cisteína/genética , Cisteína/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Proteínas de Transporte de Membrana/genética , Modelos Moleculares , Datos de Secuencia Molecular , Proteínas de Transporte de Monosacáridos/genética , Proteínas de Transporte de Monosacáridos/metabolismo , Mutación , Proteínas de Transporte de Nucleósidos/genética , Nucleósidos/genética , Alineación de Secuencia , Simportadores/química , Simportadores/genética , Simportadores/metabolismo
4.
Water Res ; 46(18): 6095-103, 2012 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-22989994

RESUMEN

For over 25 years it has been known that rotting barley straw can be used to prevent the development of blooms of cyanobacteria and algae in freshwater bodies, although its effectiveness can be variable. The mode of action is still not understood, although a number of hypotheses have been suggested, many of which are supported by little or no experimental evidence. Here, we provide the first experimental confirmation that microbial activity is responsible for the release of either the growth inhibitory fraction, or its precursor, from whole straw, after three or more weeks of decomposition. However, a much more rapid release of inhibitory components was achieved by fine chopping of fresh straw. In bioassays of straw activity the choice of both the cyanobacterial test strain and the assay temperature affected the outcome. The inhibitory activity of straw was greater when decomposition was carried out in the presence of UV-supplemented visible light and this activity was reduced in the presence of catalase, implying that straw activity may in part involve hydrogen peroxide. A better understanding of straw decomposition is required to clarify the mode of action of straw and allow the optimisation of its use in the field.


Asunto(s)
Cianobacterias/crecimiento & desarrollo , Hordeum , Bioensayo , Peróxido de Hidrógeno , Luz , Temperatura
5.
Mol Plant Microbe Interact ; 25(10): 1338-49, 2012 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-22670754

RESUMEN

Arabinogalactan proteins (AGP) are a diverse family of proteoglycans associated with the cell surfaces of plants. AGP have been implicated in a wide variety of plant cell processes, including signaling in symbioses. This study investigates the existence of putative AGP in free-living cyanobacterial cultures of the nitrogen-fixing, filamentous cyanobacteria Nostoc punctiforme and Nostoc sp. strain LBG1 and at the symbiotic interface in the symbioses between Nostoc spp. and two host plants, the angiosperm Gunnera manicata (in which the cyanobacterium is intracellular) and the liverwort Blasia pusilla (in which the cyanobacterium is extracellular). Enzyme-linked immunosorbent assay, immunoblotting, and immunofluorescence analyses demonstrated that three AGP glycan epitopes (recognized by monoclonal antibodies LM14, MAC207, and LM2) are present in free-living Nostoc cyanobacterial species. The same three AGP glycan epitopes are present at the Gunnera-Nostoc symbiotic interface and the LM2 epitope is detected during the establishment of the Blasia-Nostoc symbiosis. Bioinformatic analysis of the N. punctiforme genome identified five putative AGP core proteins that are representative of AGP classes found in plants. These results suggest a possible involvement of AGP in cyanobacterial-plant symbioses and are also suggestive of a cyanobacterial origin of AGP.


Asunto(s)
Regulación Bacteriana de la Expresión Génica/fisiología , Hepatophyta/microbiología , Magnoliopsida/microbiología , Mucoproteínas/metabolismo , Nostoc/metabolismo , Simbiosis/fisiología , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Simulación por Computador , Epítopos , Técnica del Anticuerpo Fluorescente Indirecta , Regulación de la Expresión Génica de las Plantas/fisiología , Hepatophyta/metabolismo , Magnoliopsida/metabolismo , Modelos Biológicos , Mucoproteínas/genética , Nostoc/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo
6.
ISME J ; 4(11): 1456-69, 2010 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-20505751

RESUMEN

Chlorophyll d is a photosynthetic pigment that, based on chemical analyses, has only recently been recognized to be widespread in oceanic and lacustrine environments. However, the diversity of organisms harbouring this pigment is not known. Until now, the unicellular cyanobacterium Acaryochloris marina is the only characterized organism that uses chlorophyll d as a major photopigment. In this study we describe a new cyanobacterium possessing a high amount of chlorophyll d, which was isolated from waters around Heron Island, Great Barrier Reef (23° 26' 31.2″ S, 151° 54' 50.4″ E). The 16S ribosomal RNA is 2% divergent from the two previously described isolates of A. marina, which were isolated from waters around the Palau islands (Pacific Ocean) and the Salton Sea lake (California), suggesting that it belongs to a different clade within the genus Acaryochloris. An overview sequence analysis of its genome based on Illumina technology yielded 871 contigs with an accumulated length of 8 371 965 nt. Their analysis revealed typical features associated with Acaryochloris, such as an extended gene family for chlorophyll-binding proteins. However, compared with A. marina MBIC11017, distinct genetic, morphological and physiological differences were observed. Light saturation is reached at lower light intensities, Chl d/a ratios are less variable with light intensity and the phycobiliprotein phycocyanin is lacking, suggesting that cyanobacteria of the genus Acaryochloris occur in distinct ecotypes. These data characterize Acaryochloris as a niche-adapted cyanobacterium and show that more rigorous attempts are worthwhile to isolate, cultivate and analyse chlorophyll d-containing cyanobacteria for understanding the ecophysiology of these organisms.


Asunto(s)
Clorofila/análisis , Cianobacterias/química , Cianobacterias/aislamiento & purificación , Australia , Cromatografía Líquida de Alta Presión , Análisis por Conglomerados , Cianobacterias/citología , Cianobacterias/genética , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Luz , Microscopía Electrónica de Transmisión , Datos de Secuencia Molecular , Océano Pacífico , Filogenia , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Análisis Espectral
7.
Ultramicroscopy ; 110(6): 718-22, 2010 May.
Artículo en Inglés | MEDLINE | ID: mdl-20303215

RESUMEN

Imaging signals derived from the atomic force microscope (AFM) are typically presented as separate adjacent images with greyscale or pseudo-colour palettes. We propose that information-rich false-colour composites are a useful means of presenting three-channel AFM image data. This method can aid the interpretation of complex surfaces and facilitate the perception of information that is convoluted across data channels. We illustrate this approach with images of filamentous cyanobacteria imaged in air and under aqueous buffer, using both deflection-modulation (contact) mode and amplitude-modulation (tapping) mode. Topography-dependent contrast in the error and tertiary signals aids the interpretation of the topography signal by contributing additional data, resulting in a more detailed image, and by showing variations in the probe-surface interaction. Moreover, topography-independent contrast and topography-dependent contrast in the tertiary data image (phase or friction) can be distinguished more easily as a consequence of the three dimensional colour-space.


Asunto(s)
Cianobacterias/ultraestructura , Interpretación de Imagen Asistida por Computador/métodos , Microscopía de Fuerza Atómica/métodos , Color , Aumento de la Imagen , Propiedades de Superficie
8.
EMBO J ; 27(9): 1299-308, 2008 May 07.
Artículo en Inglés | MEDLINE | ID: mdl-18388860

RESUMEN

Heterocyst-forming filamentous cyanobacteria are true multicellular prokaryotes, in which heterocysts and vegetative cells have complementary metabolism and are mutually dependent. The mechanism for metabolite exchange between cells has remained unclear. To gain insight into the mechanism and kinetics of metabolite exchange, we introduced calcein, a 623-Da fluorophore, into the Anabaena cytoplasm. We used fluorescence recovery after photobleaching to quantify rapid diffusion of this molecule between the cytoplasms of all the cells in the filament. This indicates nonspecific intercellular channels allowing the movement of molecules from cytoplasm to cytoplasm. We quantify rates of molecular exchange as filaments adapt to diazotrophic growth. Exchange among vegetative cells becomes faster as filaments differentiate, becoming considerably faster than exchange with heterocysts. Slower exchange is probably a price paid to maintain a microaerobic environment in the heterocyst. We show that the slower exchange is partly due to the presence of cyanophycin polar nodules in heterocysts. The phenotype of a null mutant identifies FraG (SepJ), a membrane protein localised at the cell-cell interface, as a strong candidate for the channel-forming protein.


Asunto(s)
Cianobacterias/citología , Cianobacterias/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Transporte Biológico , Cianobacterias/genética , Fluoresceínas/metabolismo , Recuperación de Fluorescencia tras Fotoblanqueo , Colorantes Fluorescentes/metabolismo , Microscopía Confocal
9.
J Exp Bot ; 59(5): 1047-58, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-18267939

RESUMEN

Cyanobacteria are a large group of photosynthetic prokaryotes of enormous environmental importance, being responsible for a large proportion of global CO(2) and N(2) fixation. They form symbiotic associations with a wide range of eukaryotic hosts including plants, fungi, sponges, and protists. The cyanobacterial symbionts are often filamentous and fix N(2) in specialized cells known as heterocysts, enabling them to provide the host with fixed nitrogen and, in the case of non-photosynthetic hosts, with fixed carbon. The best studied cyanobacterial symbioses are those with plants, in which the cyanobacteria can infect the roots, stems, leaves, and, in the case of the liverworts and hornworts, the subject of this review, the thallus. The symbionts are usually Nostoc spp. that gain entry to the host by means of specialized motile filaments known as hormogonia. The host plant releases chemical signals that stimulate hormogonia formation and, by chemoattraction, guide the hormogonia to the point of entry into the plant tissue. Inside the symbiotic cavity, host signals inhibit further hormogonia formation and stimulate heterocyst development and dinitrogen fixation. The cyanobionts undergo morphological and physiological changes, including reduced growth rate and CO(2) fixation, and enhanced N(2) fixation, and release to the plant much of the dinitrogen fixed. This short review summarizes knowledge of the cyanobacterial symbioses with liverworts and hornworts, with particular emphasis on the importance of pili and gliding motility for the symbiotic competence of hormogonia.


Asunto(s)
Briófitas/microbiología , Cianobacterias/fisiología , Simbiosis , Briófitas/fisiología , Dióxido de Carbono/metabolismo , Movimiento Celular , Quimiotaxis , Cianobacterias/patogenicidad , Fimbrias Bacterianas/fisiología , Fijación del Nitrógeno , Nostoc/fisiología
10.
J Bacteriol ; 190(5): 1843-7, 2008 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-18156269

RESUMEN

The filamentous cyanobacterium Nostoc punctiforme forms symbioses with plants. Disruption of the catalytic domain of the N. punctiforme adenylate cyclase (CyaC) significantly increased symbiotic competence, whereas reduced infectivity was observed in a mutant with a disruption close to the N terminus of CyaC. The total cellular cyclic AMP levels were significantly reduced in both mutants.


Asunto(s)
Adenilil Ciclasas/genética , Proteínas Bacterianas/genética , Hepatophyta/microbiología , Mutación , Nostoc/genética , Adenilil Ciclasas/metabolismo , Proteínas Bacterianas/metabolismo , AMP Cíclico/metabolismo , Modelos Genéticos , Nostoc/enzimología , Nostoc/patogenicidad , Enfermedades de las Plantas/microbiología , Virulencia/genética
11.
J Bacteriol ; 189(20): 7361-6, 2007 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-17693519

RESUMEN

Many filamentous cyanobacteria are motile by gliding, which requires attachment to a surface. There are two main theories to explain the mechanism of gliding. According to the first, the filament is pushed forward by small waves that pass along the cell surface. In the second, gliding is powered by the extrusion of slime through pores surrounding each cell septum. We have previously shown that the cell walls of several motile cyanobacteria possess an array of parallel fibrils between the peptidoglycan and the outer membrane and have speculated that the function of this array may be to generate surface waves to power gliding. Here, we report on a study of the cell surface topography of two morphologically different filamentous cyanobacteria, using field emission gun scanning electron microscopy (FEGSEM) and atomic force microscopy (AFM). FEGSEM and AFM images of Oscillatoria sp. strain A2 confirmed the presence of an array of fibrils, visible as parallel corrugations on the cell surface. These corrugations were also visualized by AFM scanning of fully hydrated filaments under liquid; this has not been achieved before for filamentous bacteria. FEGSEM images of Nostoc punctiforme revealed a highly convoluted, not parallel, fibrillar array. We conclude that an array of parallel fibrils, beneath the outer membrane of Oscillatoria, may function in the generation of thrust in gliding motility. The array of convoluted fibrils in N. punctiforme may have an alternative function, perhaps connected with the increase in outer membrane surface area resulting from the presence of the fibrils.


Asunto(s)
Pared Celular/diagnóstico por imagen , Cianobacterias/ultraestructura , Locomoción/fisiología , Pared Celular/fisiología , Cianobacterias/fisiología , Microscopía de Fuerza Atómica , Microscopía Electrónica de Rastreo , Ultrasonografía
12.
J Bacteriol ; 189(12): 4547-51, 2007 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-17416648

RESUMEN

Hormogonia are the infective agents in many cyanobacterium-plant symbioses. Pilus-like appendages are expressed on the hormogonium surface, and mutations in pil-like genes altered surface piliation and reduced symbiotic competency. This is the first molecular evidence that pilus biogenesis in a filamentous cyanobacterium requires a type IV pilus system.


Asunto(s)
Fimbrias Bacterianas/genética , Nostoc/crecimiento & desarrollo , Nostoc/genética , Plantas/microbiología , Simbiosis/genética , Secuencia de Aminoácidos , Secuencia Conservada , Fimbrias Bacterianas/fisiología , Fimbrias Bacterianas/ultraestructura , Genes Bacterianos , Microscopía Electrónica de Transmisión , Datos de Secuencia Molecular , Mutación , Nostoc/fisiología , Fenómenos Fisiológicos de las Plantas , Alineación de Secuencia
13.
Appl Environ Microbiol ; 72(9): 5713-9, 2006 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-16957185

RESUMEN

Cyanophages are viruses that infect the cyanobacteria, globally important photosynthetic microorganisms. Cyanophages are considered significant components of microbial communities, playing major roles in influencing host community diversity and primary productivity, terminating cyanobacterial water blooms, and influencing biogeochemical cycles. Cyanophages are ubiquitous in both marine and freshwater systems; however, the majority of molecular research has been biased toward the study of marine cyanophages. In this study, a diagnostic probe was developed to detect freshwater cyanophages in natural waters. Oligonucleotide PCR-based primers were designed to specifically amplify the major capsid protein gene from previously characterized freshwater cyanomyoviruses that are infectious to the filamentous, nitrogen-fixing cyanobacterial genera Anabaena and Nostoc. The primers were also successful in yielding PCR products from mixed virus communities concentrated from water samples collected from freshwater lakes in the United Kingdom. The probes are thought to provide a useful tool for the investigation of cyanophage diversity in freshwater environments.


Asunto(s)
Bacteriófagos/genética , Bacteriófagos/aislamiento & purificación , Cianobacterias/virología , Agua Dulce/microbiología , Agua Dulce/virología , Anabaena/aislamiento & purificación , Anabaena/virología , Secuencia de Bases , Cianobacterias/aislamiento & purificación , Cartilla de ADN/genética , ADN Viral/genética , Datos de Secuencia Molecular , Nostoc/aislamiento & purificación , Nostoc/virología , Reacción en Cadena de la Polimerasa , Agua de Mar/microbiología , Agua de Mar/virología
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