Sede distaccata di Pisa, Italy
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Dani K.G.S.,CNR Institute of Ecosystem Study | Dani K.G.S.,Indian Institute of Science | Loreto F.,National Research Council Italy
Trends in Plant Science | Year: 2017

Marine phytoplankton emit volatile organic compounds (VOCs) such as dimethyl sulfide (DMS) and isoprene that influence air quality, cloud dynamics, and planetary albedo. We show that globally (i) marine phytoplankton taxa tend to emit either DMS or isoprene, and (ii) sea-water surface concentration and emission hotspots of DMS and isoprene have opposite latitudinal gradients. We argue that a convergence of antioxidant functions between DMS and isoprene is possible, driven by potential metabolic competition for photosynthetic substrates. Linking phytoplankton emission traits to their latitudinal niches, we hypothesize that natural selection favors DMS emission in cold (polar) waters and isoprene emission in warm (tropical) oceans, and that global warming may expand the geographic range of marine isoprene-emitters. A trade-off between DMS and isoprene at metabolic, organismal, and geographic levels may have important consequences for future marine biosphere-atmosphere interactions. DMS and isoprene are VOCs emitted by marine phytoplankton, and their emission levels are governed by various physical (light, temperature, wind speed) and biological factors (photosynthesis, bacterial activity).Marine VOCs influence cloud formation, rain and planetary temperature, and potentially also climate change.Efforts are underway to measure DMS and isoprene simultaneously to decipher their ecological and functional roles and to improve estimates of the global marine component of VOC emission.Life-history constraints on phytoplankton biology analyzed through a functional trait-based approach is anticipated to reveal evolutionary trade-offs that may explain the current and future distribution of VOC emitters and climate change impacts on VOC emission. Global significance of volatile organic compounds emitted by marine phytoplankton. © 2017 Elsevier Ltd.

Silva-Benavides A.M.,University of Costa Rica | Torzillo G.,CNR Institute of Ecosystem Study
Journal of Applied Phycology | Year: 2012

Batch cultures of the green microalga Chlorella vulgaris and cyanobacterium Planktothrix isothrix and their corresponding co-cultures were grown in municipal wastewater in order to study their growth as well as the nitrogen (NH 4-N) and phosphorus (PO 4 3--P) removal. The cultures were grown under two irradiances of 20 and 60 μmol photons m -2 s -1 in shaken and unshaken conditions. The co-culture of unshaken Chlorella and Planktothrix showed the greatest growth under both irradiances. The monoalgal Planktotrix cultures showed better growth when unshaken than when shaken, whereas Chlorella cultures grew better when mixed, but only at the higher irradiance. The highest percentage of nitrogen removal (up to 80%) was attained by the unshaken co-cultures of Chlorella and Planktothrix. The amount of nitrogen recycled in the biomass reached up to 85% of that removed. Shaken monoalgal cultures of Chlorella showed phosphorus removal under both irradiances. They completely removed the initial phosphorus concentration (7.47 ± 0.17 mg L -1) within 96 and 48 h under 20 and 60 μmol photons m -2 s -1, respectively. © 2011 Springer Science+Business Media B.V.

Di Lorenzo T.,CNR Institute of Ecosystem Study | Galassi D.M.P.,University of L'Aquila
Fundamental and Applied Limnology | Year: 2013

In Mediterranean countries agricultural development heavily depends on groundwater availability due to arid and semi-arid climate and poor surface-water resources. Agriculture represents one of the most relevant pressures which generate impacts in alluvial aquifers by means of fertilizers and pesticides usage and groundwater overexploitation. Until now, very few studies have addressed the ecological response of groundwater fauna to groundwater contamination and overexploitation due to agricultural practices. We investigated a Mediterranean alluvial aquifer heavily affected by nitrates contamination and groundwater abstraction stress due to crop irrigation. The aim of this study was to evaluate the sensitivity of groundwater communities to (a) groundwater nitrate contamination, (b) groundwater abstraction due to irrigation practices, and (c) saltwater intrusion. The present work suggests that nitrate concentration lower than 150 mg l-1 is not an immediate threat to groundwater biodiversity in alluvial aquifers. This conclusion must be carefully considered in the light of the total lack of knowledge of the effects of long-term nitrate pollution on the groundwater biota. Moreover, local extinctions of less tolerant species, prior to monitoring, cannot be ruled out. Conversely, species abundances in ground water are affected by groundwater withdrawal, but species richness may be less sensitive. This result is attributable to the disappearance of saturated microhabitats and to the depletion of fne unconsolidated sediments, reducing the surface available to bacterial bioflm, which represent the trophic resource for several groundwater invertebrates and where the main aquifer self-purifcation processes, such as denitrifcation, take place. Saltwater intrusion seems not to affect groundwater species at the values measured in this coastal aquifer. © 2013 E. Schweizerbart'sche Verlagsbuchhandlung.

Giannelli L.,CNR Institute of Ecosystem Study | Torzillo G.,CNR Institute of Ecosystem Study
International Journal of Hydrogen Energy | Year: 2012

A new photobioreactor design (110 l) for the biological production of hydrogen with the microalga Chlamydomonas reinhardtii is presented. The photobioreactor (PBR) was made up of 64 tubes (i.d., 27.5 mm, length, 2 m) arranged on an 8 × 8 square pitch cell connected by 64 U-bends for a total length of 133 m. The PBR was contained in a rectangular parallelepiped tank (2.5 × 2 × 2 m) made with isotactic polypropylene, except for the opposite square faces which were made of transparent Plexiglas. The tubes were immersed in a thermostatic water bath and continuously illuminated with artificial light. The culture was circulated with a peristaltic pump. To attain a uniform distribution of light to the cells, we used a suspension of silica nanoparticles that scattered the light supplied by the light bulbs (2 × 2000 W) from the opposite square sides of the photobioreactor. Growth experiments carried out with C. reinhardtii CC124 strain, showed a 23% net increase in the final chlorophyll concentration when the nanoparticle suspension was used. Hydrogen production with the C. reinhardtii strain CC124 was investigated with the new photobioreactor design and carried out using a direct inoculum of sulfur-limited cultures having a residual sulfate concentration below 1 mg l -1. The mean hydrogen output was 3121.5 ± 178.9 ml. The reactor fluid dynamic was investigated, and a tri-dimensional light profile inside the PBR is reported. Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights.

Padovani G.,CNR Institute of Ecosystem Study | Pintucci C.,CNR Institute of Ecosystem Study | Carlozzi P.,CNR Institute of Ecosystem Study
Bioresource Technology | Year: 2013

This investigation deals with the conversion of olive-mill wastewater (OMW) into several feedstocks suitable for hydrogen photo-production. The goal was reached by means of two sequential steps: (i) a pre-treatment process of stored-OMW for the removal of polyphenols, which made it possible to obtain several effluents, and (ii) a photo-fermentative process for hydrogen production by means of Rhodopseudomonas palustris sp. Four different adsorbent matrices (Azolla, granular active carbon, resin, and zeolite) were used to dephenolize stored-OMW. The four liquid fractions attained by using the above process created the same number of effluents, and these were diluted with water and then used for hydrogen photo-production. The maximum hydrogen production rate (14.31. mL/L/h) was attained with the photo-fermenter containing 25% of the effluent, which came from the pre-treatment of stored-OMW using granular active carbon. Using the carbon effluent as feedstock, the greatest light conversion efficiency of 2.29% was achieved. © 2013 Elsevier Ltd.

Callieri C.,CNR Institute of Ecosystem Study
Journal of Limnology | Year: 2010

Picocyanobacteria (Pcy) single-cells and microcolonies are common in lakes throughout the world, and abundant across a wide spectrum of trophic conditions. The single-celled Pcy populations tend to be predominant in large, deep oligo-mesotrophic lakes, while the microcolonies find optimal conditions in warmer, shallower and more nutrient rich lakes. Microcolonies of different size (from 5 to 50 cells) constitute a gradient without a net separation from single-celled types. Considering microcolonies as transitional forms from single-cells to colonial morphotypes it is conceivable to propose a common ecology where local communities are not isolated but linked by dispersal of multiple, potentially interactive, species. In this review abiotic forcing and biotic regulation of Pcy community structure and dynamics are examined to offer an updated view of Pcy ecology.

Faraloni C.,CNR Institute of Ecosystem Study | Torzillo G.,CNR Institute of Ecosystem Study
Journal of Phycology | Year: 2010

The effects of QB-binding D1-protein mutations on the phenotypic characteristics and on hydrogen production of sulfur-deprived Chlamydomonas reinhardtii P. A. Dang. cultures were investigated. The mutation involved one (D240) or double (D239-40) amino-acid deletions at positions 240 and 239-240, respectively, in the loop connecting helices D and E of the D1 protein. Phenotypic characterization of the mutants showed the following peculiarities as compared to the wildtype (WT): (i) a higher sensitivity to photoinhibition, (ii) a reduced amount of chl per dry weight and per cell, (iii) a higher respiration-to-photosynthesis ratio, (iv) a higher carbohydrate accumulation during the aerobic phase, and (v) a higher synthesis of xanthophyll-cycle pigments. These differences were translated into a 12- to 18-fold higher hydrogen biogas production. © 2010 Phycological Society of America.

Taiti S.,CNR Institute of Ecosystem Study
Tropical Zoology | Year: 2014

Twenty-seven species of terrestrial isopods are recorded from the Maldive Islands (North Kaafu Atoll and Vaavu Atoll). One genus (Eubelinum) in the family Eubelidae and three species (Styloniscusmaldivensis, Eubelinumincertum, and Pseudodiploexochusindicus) are described as new, and 26 species are newly recorded from the archipelago. Ligia dentipes Budde-Lund, 1885 is also recorded from Sri Lanka and Seychelles. The poorly known species Tylosalbidus Budde-Lund, 1885 and Platyarthrus acropyga Chopra, 1924 are also illustrated. The composition and origin of the oniscidean fauna of the Maldives are briefly discussed. D3C8A0B23848 © 2014 Istituto per lo Studio degli Ecosistemi of the Consiglio Nazionale delle Ricerche, Firenze .

Carlozzi P.,CNR Institute of Ecosystem Study
Journal of Biomedicine and Biotechnology | Year: 2012

The main goal of this study was to increase the hydrogen production rate improving the culture technique and the photobioreactor performances. Experiments were carried out at a constant culture temperature of 30°C and at an average irradiance of 480Wm -2 using a cylindrical photobioreactor (4.0cm, internal diameter). The culture technique, namely, the semicontinuous regime for growing Rhodopseudomonas palustris 42OL made it possible to achieve a very high daily hydrogen production rate of 594 ± 61mL (H2) L -1d -1. This value, never reported for this strain, corresponds to about 25mL (H2) L -1h -1, and it was obtained when the hydraulic retention time (HRT) was of 225 hours. Under the same growth conditions, a very high biomass production rate (496 45mg (dw) L -1d -11) was also achieved. Higher or lower HRTs caused a reduction in both the hydrogen and the biomass production rates. The malic-acid removal efficiency (MAre) was always higher than 90. The maximal hydrogen yield was 3.03mol H2 mol MA -1 at the HRT of 360 hours. The highest total energy conversion efficiency was achieved at the HRT of 225 hours. © Copyright 2012 Pietro Carlozzi.

Fontaneto D.,CNR Institute of Ecosystem Study | Hortal J.,CSIC - National Museum of Natural Sciences
Molecular Ecology | Year: 2013

Body size is one of the main regulators of the ecological characteristics of living organisms, including their biogeography. The 'ubiquity hypothesis' for microorganisms states that they are widely distributed, if not cosmopolitan, due to their small size that allows passive dispersal, in contrast to large organisms that are limited by geographical barriers in their active dispersal. Such idea, summarized in the tenet 'Everything is everywhere, but the environment selects', has driven most of the research in biogeography for microscopic organisms in the last decades, spurring a debate on whether there are fundamental differences in the biogeography of small and large organisms or not (Fenchel & Finlay 2004; Foissner 2008; Hortal 2011). The strong focus on the ubiquity hypothesis may have been often abused to provide a rationale for otherwise descriptive work on the spatial distribution of microscopic organisms; nevertheless, such focus also provides a framework to understand the mechanisms originating and maintaining biodiversity in space. The reliability of the analyses on unknown and understudied organisms is improving, and Heger et al. (2013) is a splendid example on small unicellular eukaryotes of what should be done to overcome the major problems and ambiguities that heated the debate on the ubiquity hypothesis. © 2013 John Wiley & Sons Ltd.

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