210 research outputs found
Capsular polysaccharides of cultured phototrophic biofilms
Phototrophic biofilm samples from an Italian wastewater treatment plant were studied in microcosm experiments under varying irradiances, temperatures and flow regimes to assess the effects of environmental variables and phototrophic biomass on capsular exopolysaccharides (CPS). The results, obtained from circular dichroism spectroscopy and High Performance Liquid Chromatography, suggest that CPS have a stable spatial conformation and a complex monosaccharide composition. The total amount present was positively correlated with the biomass of cyanobacteria and diatoms, and negatively with the biovolume of green algae. The proportion of uronic acids showed the same correlation with these taxon groups, indicating a potential role of cyanobacteria and diatoms in the removal of residual nutrients and noxious cations in wastewater treatment. While overall biofilm growth was limited by low irradiance, high temperature (30 degrees C) and low flow velocity (25 l h(-1)) yielded the highest phototrophic biomass, the largest amount of CPS produced, and the highest proportion of carboxylic acids present
Characterization for biofilm-forming cyanobacteria for biomass and lipid production
Aims: This work reports on one of the first attempts to use biofilm-forming
cyanobacteria for biomass and lipid production.
Methods and Results: Three isolates of filamentous cyanobacteria were
obtained from biofilms at different Italian sites and characterized by a
polyphasic approach, involving microscopic observations, ecology and genetic
diversity (studying the 16S rRNA gene). The isolates were grown in batch
systems and in a semi-continuous flow incubator, specifically designed for
biofilms development. Culture system affected biomass and lipid production,
but did not influence the fatty acid profile. The composition of fatty acids was
mainly palmitic acid (>50%) and less amounts of other saturated and
monounsaturated fatty acids. Only two isolates contained two polyunsaturated
fatty acids.
Conclusions: Data obtained from the flow-lane incubator system would
support a more economical and sustainable use of the benthic microorganisms
for biomass production. The produced lipids contained fatty acids
suitable for a high-quality biodiesel production, showing high proportions of
saturated and monounsaturated fatty acids.
Significance and Impact of the Study: Data seem promising when taking into
account the savings in cost and time derived from easy procedures for biomass
harvesting, especially when being able to obtain the co-production of other
valuable by-products
DNA barcoding of Ceramiales (Rhodophyta) around the Maltese islands reveals hidden biodiversity in the central Mediterranean
The genetic biodiversity of Mediterranean macroalgae is
generally understudied, a fact which is especially important
in the case of morphologically cryptic taxa. As a result, it is
often challenging to compare DNA barcodes from
Mediterranean samples to references in online databases
since, very often, no close hits are available. At a regional
scale, of around 1124 records of algae in the Mediterranean
Sea, only 114 species have been barcoded.peer-reviewe
Contact X-ray microscopy of living cells by using LiF crystal as imaging detector
In this paper, the use of lithium fluoride (LiF) as imaging
radiation detector to analyse living cells by single-shot soft
X-ray contact microscopy is presented. High resolved X-ray
images on LiF of cyanobacterium Leptolyngbya VRUC135,
two unicellular microalgae of the genus Chlamydomonas
and mouse macrophage cells (line RAW 264.7) have been
obtained utilizingX-ray radiation in the water window energy
range from a laser plasma source. The used method is based on
loading of the samples, the cell suspension, in a special holder
where they are in close contactwith a LiF crystal solid-state Xray
imaging detector. After exposure and sample removal, the
images stored in LiF by the softX-ray contactmicroscopy technique
are read by an optical microscope in fluorescence mode.
The clear image of the mucilaginous sheath the structure
of the filamentous Leptolyngbya and the visible nucleolus in
the macrophage cells image, are noteworthiness results. The
peculiarities of the used X-ray radiation and of the LiF imaging
detector allow obtaining images in absorption contrast revealing
the internal structures of the investigated samples at high
spatial resolution. Moreover, thewidedynamicrangeof theLiF
imaging detector contributes to obtain high-quality images. In
particular, we demonstrate that this peculiar characteristic of
LiF detector allows enhancing the contrast and reveal details
even when they were obscured by a nonuniform stray light
Maximum rates of N2 fixation and primary production are out of phase in a developing cyanobacterial bloom in the Baltic Sea
Although N2-fixing cyanobacteria contribute significantly to oceanic sequestration of atmospheric CO2, little is known about how N2 fixation and carbon fixation (primary production) interact in natural populations of marine cyanobacteria. In a developing cyanobacterial bloom in the Baltic Sea, rates of N2 fixation (acetylene reduction) showed both diurnal and longer-term fluctuations. The latter reflected fluctuations in the nitrogen status of the cyanobacterial population and could be correlated with variations in the ratio of acetylene reduced to 15N2 assimilated. The value of this ratio may provide useful information about the release of newly fixed nitrogen by a cyanobacterial population. However, although the diurnal fluctuations in N2 fixation broadly paralleled diurnal fluctuations in carbon fixation, the longer-term fluctuations in these two processes were out of phase
Cryptic dispersal of Cyanidiophytina (Rhodophyta) in non-acidic environments from Turkey
Cyanidiophytina are a group of polyextremophilic red algae with a worldwide, but discontinuous colonization. They are restricted to widely dispersed hot springs, geothermal habitats, and also some human-altered environments. Cyanidiophytina are predominant where pH is prohibitive for the majority of eukaryotes (pH 0.5-3). Turkey is characterized by areas rich in volcanic activity separated by non-volcanic areas. Here we show that Cyanidiophycean populations are present in thermal baths located around Turkey on neutral/alkaline soils. All known genera and species within Cyanidiophytina were detected in Turkey, including Galdieria phlegrea, recorded up to now only in Italian Phlegrean Fields. By phylogenetic analyses, Turkish G. sulphuraria strains are monophyletic with Italian and Icelandic strains, and with Russian G. daedala strains. G. maxima from Turkey clustered with Icelandic, Kamchatka, and Japanese populations. The discovery of Cyanidiophytina in non-acidic Turkish soils raises new questions about the ecological boundaries of these extremophilic algae. This aids in the understanding of the dispersal abilities and distribution patterns of this ecologically and evolutionarily interesting group of algae
Mechanisms of Acido-Tolerance and Characteristics of Photosystems in an Acidophilic and Thermophilic Red Alga, Cyanidium Caldarium
In this chapter, we describe the mechanisms of acido-tolerance in an acidophilic- and thermophilic red alga, Cyanidium caldarium. In spite of the extremely acidic environments it inhabits, the intracellular pH of Cyanidium cells is kept neutral by pumping out the protons previously leaked into the cells according to the steep pH gradient. The H+ pump is driven by the plasma membrane ATPase, utilizing intracellular ATP produced by both oxidative phosphorylation and cyclic photophosphorylation via photosystem I. We also describe the characteristics and function of the two photosystems, Photosystem I (PSI) and II (PSII), in Cyanidium caldarium in comparison with those of cyanobacteria, other eukaryotic algae, and higher plants, based on the crystal structures of the two complexes reported so far
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