406 research outputs found
A Multi Size-Level Assessment of Benthic Marine Communities in a Coastal Environment: Are They Different Sides of the Same Coin?
No full textOrganism body size has been demonstrated to be a discriminating element in shaping the response of living beings to environmental factors, thus playing a fundamental role in community structuring. Despite the importance of studies elucidating relations among communities of different size levels in ecosystems, the attempts that have been made in this sense are still very scarce and a reliable approach for these research still has to be defined. We characterized the benthic communities of bacteria, microbial eukaryotes, meiofauna and macrofauna in a coastal environment, encompassing a 10000-fold gradient in body size, testing and discussing a mixed approach of molecular fingerprinting for microbes and morphological observations for meio- and macrofauna. We found no correlation among structures of the different size-level communities: this suggests that community composition at one size-level could have no (or very low) influence on the community composition at other size-levels. Moreover, each community responds in a different way to the environmental parameters and with a degree of sensitivity which seems to increase with organism size. Therefore, our data indicate that the characterization of all the different size levels is clearly a necessity in order to study the dynamics really acting in a system
A symbiotic bacterium compensates for a glycogen metabolism genetic disorder in ciliates
No full textPolynucleobacter: Symbiotic bacteria in ciliates compensate for a genetic disorder in glycogenolysis
No full textCiliates of a group of closely related species of the genus Euplotes harbor Polynucleobacter bacteria, and apparently need them in order to successfully reproduce. In the present paper we investigate the possible metabolic correlation between the two partners in this symbiosis. We examine and compare behavioral, ultrastructural and cytochemical analysis specimens of E. harpa, with and without their symbionts. The results show that aposymbiotic cells do not undergo a sharp blockage of their cell cycle: they are able to start and go on with DNA replication and, in some cases, nuclear division; in a few cases they can even start cytoplasmic division. Electron microscopical observation reveals that these cells are no longer able to perform glycogenolysis. A similar deficiency was observed in aposymbiotic E. aediculatus. In all likelihood, this failure deprives them of an important energy source useful for the accomplishment of the energetically costly fission process. These results are in agreement with the assumption that the bacteria compensate for their hosts’ metabolic disorder and prove that this disorder concerns glycogen metabolism. The fact that Polynucleobacter-like bacteria are present in every organism of several different, closely correlated, Euplotes species and are vertically transmitted from generation to generation, indicates that we are dealing with a hereditary disorder, possibly an enzymatic deficiency, as happens in the human genetic diseases referred to as glycogenosis, and that the bacteria make up for this deficiency
Benthic bacterial and eukaryotic microbial communities: characterization and comparative analysis along an anthropogenic pollution gradient.
No full textCharacterization of prokaryotic communities from Italian super-heated fumaroles
No full textAmong extremophiles, thermophile microorganisms from geothermal sites have been widely studied. Nevertheless, our knowledge is still relatively poor on microbial communities colonizing fumaroles, which are super-ephemeral habitats, characterized by an only intermittent presence of water. Here we characterized by metabarcoding both bacterial and archaeal communities from hot spring waters and biofilms, together with dry and wet fumaroles, of a geothermal basin in central Italy. Taxa composition of the analyzed samples mirrored that of previous studies, with Thermoproteota dominating among Archaea, while high percentages of thermophiles and spore-forming organisms were retrieved for Bacteria. Cyanobacteriota were the dominant group in biofilms. Community structure was different in the two domains, with highly selected communities of Archaea, less diversified than bacterial ones. Linear regression analyses highlighted significant correlations between diversity and environmental parameters in dry, but not in wet fumaroles. Although ASV numbers displayed different trends for the two different prokaryotic domains (positive correlation with pH for Bacteria, negative correlation for both pH and T for Archaea), such results indicate that even an extremely ephemeral presence of water can influence the importance of temperature and pH as drivers for microbial community structure
Polynucleobacter bacteria in the brackish water species Euplotes harpa (Ciliata Hypotrichia)
No full textABSTRACT. We have found a Polynucleobacter bacterium in the cytoplasm of Euplotes harpa, a species living in a brackish-water habitat, with a cirral pattern not corresponding to that of the freshwater Euplotes species known to harbor this type of bacteria. The symbiont has been found in three strains of the species, obtained by clonal cultures from ciliates collected in different geographic regions.
The 16S rRNA gene sequence of this bacterium identifies it as a member of the b-proteobacterial genus Polynucleobacter. This sequence shares a high similarity value (98.4–98.5%) with P. necessarius, the type species of the genus, and is associated with 16S rRNA gene sequences of environmental clones and bacterial strains included in the Polynucleobacter cluster (495%). An oligonucleotide probe was designed to corroborate the assignment of the retrieved sequence to the symbiont and to detect similar bacteria rapidly. Antibiotic experiments showed that the elimination of the bacteria stops the reproductive cycle in E. harpa, as has been shown for the freshwater Euplotes species
Wild Avian Gut Microbiome at a Small Spatial Scale: A Study from a Mediterranean Island Population of Alectoris rufa
No full textThis research is one of the few comparative descriptions at an intraspecific level of wild non-passerine microbiomes. We investigated for the first time the gut microbiome of red-legged partridges (Alectoris rufa) using fecal pellets in order to provide a more informed management. We focused on a small Italian population consisting of two demes (WEST, EAST) separated by about 20 km on the opposite sides of Elba Island. Given the small spatial scale, we set up a sampling protocol to minimize contamination from environmental bacteria, as well as differences due to variations in—among others—habitat, season, and age of feces, that could possibly affect the investigation of the three Elban sites. We found a significant divergence between the WEST and EAST Elban subpopulations in terms of microbial composition and alpha diversity. Although most represented bacterial phyla were the same in all the sites (Firmicutes, Actinobacteria, Proteobacteria, and Bacteroidetes), microbiomes displayed a much higher diversity in western than in eastern partridges. This result might be related to locally diverging individual physiological needs and/or to different intensities in past releases of captive-bred birds between the two sides of Elba. We suggest that the two subpopulations should be treated as distinct management units
Pratiche di apprendimento e formazione nei contesti di lavoro
No full textIl presente progetto di ricerca si situa all’interno del framework teorico degli studi sociomateriali. In particolare, La ricerca intende studiare quali sono gli oggetti della formazione generati da un ecosistema formativo e come tali oggetti vengono promossi. Il disegno della ricerca di tipo qualitativo utilizza uno studio di caso che ha permesso la raccolta di 10 interviste semi-strutturate e note derivanti dall’osservazione partecipante. È stata indagata un’azienda italiana nel settore dell’ICT al cui interno è presente da alcuni anni una Academy aziendale, studiata come esempio di un ecosistema formativo che sta crescendo e che incorpora elementi di innovazione e di sperimentazione formativa
The microbial community in a moving bed biotrickling filter operated to remove hydrogen sulfide from gas streams
No full textThe information available on the microbial communities responsible for pollutant degradation is increasingly accessible. Its use to optimize process design and operation is an important challenge in the field of effluent treatment research. Therefore, a prototype of a moving bed biotrickling filter (MBBTF) reactor was designed and, for the first time, operated at full-scale for the removal of sulfides desorbing from tannery industrial wastewater. The bacterial community operating in this innovative reactor was studied, and its composition and response to different operating conditions were characterized. A stable biomass, dominated by sulfur-oxidizing bacteria of the genus Acidithiobacillus was selected from inside the MBBTF reactor, and temperature, pH and bed rotation were shown to be the main factors driving the community structure. Moreover, data from different approaches indicated an uneven spatial distribution of biofilm inside the studied reactor, due to the combined effect of fluid dynamics and substrate gradients within the bed volume. Despite the high removal efficiency achieved by this innovative prototype (80% on average), the data suggested that the result could be improved by adopting solutions for a more stable and even biofilm distribution. It was shown that short frequent bed rotations, rather than long scattered rotations, ensured biomass stability. Furthermore, diversifying biofilm support media as a function of expected local pollutant concentrations should be considered. Data obtained from the bacterial community can therefore provide indications for possible further improvement of MBBTF reactor design and performance
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