Differential Antimicrobial Effect of Three-Sized Biogenic Silver Nanoparticles as Broad-Spectrum Antibacterial Agents against Plant Pathogens.

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.

Use of molecular modelling to probe the mechanism of the nucleoside transporter NupG.

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.

A silicon cell cycle in a bacterial model of calcium phosphate mineralogenesis.

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).

A series of experiments aimed at clarifying the mode of action of barley straw in cyanobacterial growth control.

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.

Arabinogalactan proteins occur in the free-living cyanobacterium genus Nostoc and in plant-Nostoc symbioses.

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.

A new chlorophyll d-containing cyanobacterium: evidence for niche adaptation in the genus Acaryochloris.

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.

Three-channel false colour AFM images for improved interpretation of complex surfaces: a study of filamentous cyanobacteria.

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.

Mechanism of intercellular molecular exchange in heterocyst-forming cyanobacteria.

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.

Cyanobacteria-bryophyte symbioses.

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.

Mutation at different sites in the Nostoc punctiforme cyaC gene, encoding the multiple-domain enzyme adenylate cyclase, results in different levels of infection of the host plant Blasia pusilla.

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.

Nanoscale visualization of a fibrillar array in the cell wall of filamentous cyanobacteria and its implications for gliding motility.

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.

Molecular analysis of genes in Nostoc punctiforme involved in pilus biogenesis and plant infection.

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.

Identification of a diagnostic marker to detect freshwater cyanophages of filamentous cyanobacteria.

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.