108 research outputs found
An innovative respirometric method to assess the autotrophic active fraction: Application to an alternate oxic-anoxic MBR pilot plant
An innovative respirometric method was applied to evaluate the autotrophic active fraction in an alternate anoxic/oxic membrane bioreactor (MBR) pilot plant. The alternate cycle (AC) produces a complex microbiological environment that allows the development of both autotrophic and heterotrophic species in one reactor. The present study aimed to evaluate autotrophic and heterotrophic active fractions and highlight the effect of different aeration/non aeration ratios in a AC-MBR pilot plant using respirometry. The results outlined that the autotrophic active fraction values were consistent with the nitrification efficiency and FISH analyses, which suggests its usefulness for estimating the nitrifying population. Intermittent aeration did not significantly affect the heterotrophic metabolic activity but significantly affected the autotrophic biomass development. Finally, the heterotrophic active biomass was strongly affected by the wastewater characteristics, whereas the resultant autotrophic biomass was considerably affected by the duration of the aerated phase
Diversity and biomass accumulation in cultured phototrophic biofilms
In the present study, biomass development and changes in community composition of phototrophic biofilms grown under different controlled ambient conditions (light, temperature and flow) were examined. Source communities were taken from a wastewater treatment plant and used to inoculate growth surfaces in a semi-continuous-flow microcosm. We recorded biofilm growth curves in cultures over a period of 30 days across 12 experiments. Biovolume of phototrophs and community composition for taxonomic shifts were also obtained using light and electron microscopy. Species richness in the cultured biofilms was greatly reduced with respect to the natural samples, and diversity decreased even further during biofilm development. Diadesmis confervacea, Phormidium spp., Scenedesmus spp. and Synechocystis spp. were identified as key taxa in the microcosm. While a significant positive effect of irradiance on biofilm growth could be identified, impacts of temperature and flow rate on biofilm development and diversity were less evident. We discuss the hypothesis that biofilm development could have been subject to multistability, i.e. the existence of several possible stable biofilm configurations for the same set of environmental parameters; small variations in the species composition might have been sufficient to switch between these different configurations and thus have contributed to overwriting the original effects of temperature and flow velocity
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
Characterization of exopolysaccharides produced by seven biofilm-forming cyanobacterial strains for biotechnological applications
The molecular identification of seven biofilmforming
cyanobacteria and the characterization of their
exopolysaccharides were made and considered in terms of
potential biotechnological applications. The studied strains
were isolated from phototrophic biofilms taken from various
Italian sites including a wastewater treatment plant, an eroded
soil, and a brackish lagoon. The polysaccharides were
characterized by use of ion exchange chromatography,
circular dichroism, and cytochemical stains. All strains produced
exopolysaccharides with differing ratios of hydrophobic
and hydrophilic moieties depending on the species, the
polysaccharide fraction (i.e., whether capsular or released),
and the ambient conditions. It was shown that the anionic
nature of the exopolysaccharides was due to the presence of
carboxylic and sulfated groups and is likely the main characteristic
with industrial applicability. Potential biotechnological
applications are discusse
The Open Universe survey of Swift-XRT GRB fields: a complete sample of HBL blazars
We have analysed all the X-ray images centred on Gamma Ray Bursts generated
by Swift over the last 15 years using automatic tools that do not require any
expertise in X-ray astronomy, producing results in excellent agreement with
previous findings. This work, besides presenting the largest medium-deep survey
of the X-ray sky and a complete sample of blazars, wishes to be a step in the
direction of achieving the ultimate goal of the Open Universe Initiative, that
is to enable non expert people to fully benefit of space science data, possibly
extending the potential for scientific discovery, currently confined within a
small number of highly specialised teams, to a much larger population. We have
used the Swift_deepsky Docker container encapsulated pipeline to build the
largest existing flux-limited and unbiased sample of serendipitous X-ray
sources. Swift_deepsky runs on any laptop or desktop computer with a modern
operating system. The tool automatically downloads the data and the calibration
files from the archives, runs the official Swift analysis software and produces
a number of results including images, the list of detected sources, X-ray
fluxes, SED data, and spectral slope estimations. We used our source list to
build the LogN-LogS of extra-galactic sources, which perfectly matches that
estimated by other satellites. Combining our survey with multi-frequency data
we selected a complete radio flux-density limited sample of High Energy Peaked
(HBL) blazars.Comment: Accepted for publication in A&A. 8 pages, 7 figure
Open Universe for Blazars: A new generation of astronomical products based on 14 years of Swift -XRT data
Aims. Open Universe for Blazars is a set of high-transparency multi-frequency data products for blazar science, and the tools designed to generate them. Blazars are drawing growing interest following the consolidation of their position as the most abundant type of source in the extragalactic very high-energy γ-ray sky, and because of their status as prime candidate sources in the nascent field of multi-messenger astrophysics. As such, blazar astrophysics is becoming increasingly data driven, depending on the integration and combined analysis of large quantities of data from the entire span of observational astrophysics techniques. The project was therefore chosen as one of the pilot activities within the United Nations Open Universe Initiative, whose objective is to stimulate a large increase in the accessibility and ease of utilisation of space science data for the worldwide benefit of scientific research, education, capacity building, and citizen science. Methods. Our aim is to deliver innovative data science tools for multi-messenger astrophysics. In this work we report on a data analysis pipeline called Swift-DeepSky based on the Swift XRTDAS software and the XIMAGE package, encapsulated into a Docker container. Swift-DeepSky downloads and reads low-level data, generates higher level products, detects X-ray sources, and estimates several intensity and spectral parameters for each detection, thus facilitating the generation of complete and up-to-date science-ready catalogues from an entire space-mission data set. Results. As a first application of our innovative approach, we present the results of a detailed X-ray image analysis based on Swift-DeepSky that was run on all Swift-XRT observations including a known blazar, carried out during the first 14 years of operations of the Neil Gehrels Swift Observatory. Short exposures executed within one week of each other have been added to increase sensitivity, which ranges between ∼1 × 10-12 and ∼1 × 10-14 erg cm-2 s-1 (0.3-10.0 keV). After cleaning for problematic fields, the resulting database includes over 27 000 images integrated in different X-ray bands, and a catalogue, called 1OUSXB, that provides intensity and spectral information for 33 396 X-ray sources, 8896 of which are single or multiple detections of 2308 distinct blazars. All the results can be accessed online in a variety of ways, from the Open Universe portal through Virtual Observatory services, via the VOU-Blazar tool and the SSDC SED builder. One of the most innovative aspects of this work is that the results can be easily reproduced and extended by anyone using the Docker version of the Swift-DeepSky pipeline, which runs on Linux, Mac, and Windows machines, and does not require any specific experience in X-ray data analysis.Fil: Giommi, Paolo. Università di Roma; Italia. International Center For Relativistic Astrophysics; Italia. Universitat Technical Zu Munich; AlemaniaFil: Brandt, C. H.. International Center For Relativistic Astrophysics; Italia. Jacobs University; AlemaniaFil: Barres de Almeida, U.. International Center For Relativistic Astrophysics; Italia. Centro Brasileiro de Pesquisas FÃsicas; BrasilFil: Pollock, A. M. T.. University of Sheffield; Reino UnidoFil: Arneodo, F.. New York University Abu Dhabi; Arabia SauditaFil: Chang, Y. L.. International Center For Relativistic Astrophysics; ItaliaFil: Civitarese, Enrique Osvaldo. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - La Plata. Instituto de FÃsica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de FÃsica La Plata; ArgentinaFil: de Angelis, Maria Cruz. Università di Roma; ItaliaFil: D'Elia, V.. Space Science Data Center; Italia. Osservatorio Astronomico di Roma; ItaliaFil: Del Rio Vera, J.. United Nations Office for Outer Space Affairs; AustraliaFil: Di Pippo, S.. United Nations Office for Outer Space Affairs; AustraliaFil: Middei, Riccardo. Università di Roma; ItaliaFil: Penacchioni, Ana Virginia. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - La Plata. Instituto de FÃsica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de FÃsica La Plata; ArgentinaFil: Perri, M.. Osservatorio Astronomico di Roma; Italia. Space Science Data Center; ItaliaFil: Ruffini, Remo. International Center For Relativistic Astrophysics; ItaliaFil: Sahakyan, Narek. International Centre For Relativistic Astrophysics Network; ArmeniaFil: Turriziani, Sara. Computational Astrophysics Laboratory; Japó
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