177,069 research outputs found
R. MARTORELLI, M. MURESU, Introduzione, in R. MARTORELLI, M. MURESU (eds.), L’alimentazione nel Mediterraneo dalla Tarda antichità al Medioevo. Dalla Sardegna alla Spagna/Food in the Mediterranean from Late Antiquity to Middle Age. From Sardinia to Spain = Pubblicazioni del Dipartimento di Storia, Beni culturali e Territorio dell’Università degli Studi di Cagliari. Archeologia, arte e storia, 6, Perugia: Morlacchi Editore U.P., 2017, pp. 11-12; ISBN: 978-88-6074-940-6.
No full textR. MARTORELLI, M. MURESU (eds.), L’alimentazione nel Mediterraneo dalla Tarda antichità al Medioevo. Dalla Sardegna alla Spagna/Food in the Mediterranean from Late Antiquity to Middle Age. From Sardinia to Spain = Pubblicazioni del Dipartimento di Storia, Beni culturali e Territorio dell’Università degli Studi di Cagliari. Archeologia, arte e storia, 6, Perugia: Morlacchi Editore U.P., 2017; ISBN: 978-88-6074-940-6.
No full textPCR primers based on different portions of insertion elements can assist phylogeny studies, strain fingerprinting and species identification in rhizobia.
No full textUsing the sequence of an insertion element originally found in Rhizobium sullae, the nitrogen-fixing bacterial symbiont of the legume Hedysarum coronarium, we devised three primer pairs (inbound, outbound and internal primers) for the following applications: (a) tracing genetic relatedness within rhizobia using a method independent of ribosomal inheritance, based on the presence and conservation of IS elements; (b) achieve sensitive and reproducible bacterial fingerprinting; (c) enable a fast and unambiguous detection of rhizobia at the species level. In terms of taxonomy, while in line with part of the 16S rRNA gene- and glutamine synthetase I-based clustering, the tools appeared nonetheless more coherent with the actual geographical ranges of origin of rhizobial species, strengthening the European-Mediterranean connections and discerning them from the asian and american taxa. The fingerprinting performance of the outward-pointing primers, designed upon the inverted repeats, was shown to be at least as sensitive as BOX PCR, and to be functional on a universal basis with all 13 bacterial species tested. The primers designed on the internal part of the transposase gene instead proved highly species-specific for R. sullae, enabling selective distinction from its most related species, and testing positive on every R. sullae strain examined, fulfilling the need of PCR-mediated species identification. A general use of other IS elements for a combined approach to rhizobial taxonomy and ecology is proposed
Characterization of endophytic and symbiotic bacteria within plants of the endemic association Centaureetum horridae Mol.
No full textWe investigated the internal association of bacteria with Astragalus terraccianoi and Centaurea horrida, two endemic plants of the Mediterranean islands, forming the phytosociological association Centaureetum horridae, typical of windswept cliffs on the rocky shores of Asinara (Sardinia, Italy) and other limited locations. Sampling occurred in the protected natural park of the Asinara island. Roots and stems of the two plants and the root nodules of A. terraccianoi were surface sterilized in order to remove external and rhizospheric microbiota and to subsequently isolate the culturable bacterial communities. Plate counts revealed densities of endophytes between 3.7 × 102 and 2.8 × 104 colony forming units per gram of fresh weight. 16S rDNA sequencing revealed the occurrence of bacteria displaying high similarity with Actinobacterium sp., Paenibacillus sp., Rhizobium sp., Methylobacterium sp., Pedobacter panaciterrae, Aerococcus viridans, Stenotrophomonas rhizophila, Bacillus sporothermodurans, Bacillus pumilus, Bacillus simplex, Bacillus flexus, Streptomyces ciscaucasicus and Dyella sp. The putative nitrogen-fixing rhizobium symbiont of A. terraccianoi was identified for the first time. It turned out to belong to the slow-growing Bradyrhizobium genus and to share a 97% similarity with Bradyrhizobium canariense. It was found to be nonculturable and to coexist in nodules with a number of different endophytes
Nitrogen fixation of Sulla under Mediterranean conditions
No full textSulla coronaria (L.) B.H. Choi & H. Ohashi (=Hedysarum coronarium L.) is a Mediterranean forage legume grown extensively
in rainfed Italian environments. Here we report the field quantification of its seasonal and annual N fixation, using the 15N isotopic
dilution (ID) method, the infl uence of various non fixing reference species on these estimates, and the allocation of fixed N between the aerial and the belowground biomass. Parallel experiments were conducted over two biennial crop cycles at two Italian
locations (Sassari and Ancona), characterized by sandy-loam to heavy clay-loam calcareous soils. The proportion of nitrogen
derived from the atmosphere (%Ndfa) present in the aerial biomass reached 78.2% at Sassari and 82.7% at Ancona, with no significant effect of the identity of the non fixing reference species. At Sassari, the amount of fixed N present in the aerial dry matter
(DM) of sulla was 187 kg ha−1 in the first crop cycle, and 265 kg ha−1 in the second, while the equivalent N yields at Ancona were 350 and 170 kg ha−1. The relationship between the quantity of fixed N in the aerial biomass and the aerial DM yield of sulla was
significant and not site-specific, realizing an equivalence of about 1.8 kg ha−1 of fi xed N per 100 kg ha−1 of aerial DM. Th e relative
contribution of the root biomass to the amount of fi xed N was on average 4%. The N balance of sulla at the end of the second crop cycle was negative, but the N sparing effect compared with the non fixing species ranged from 65 to 175 kg ha−1
Bacteria colonizing root nodules of wild legumes exhibit virulence-associated properties of mammalian pathogens.
No full textBacteria not proficient in nitrogen fixing symbiosis were proven able to invade root nodules of three wild legumes of the genus Hedysarum in Algeria and to be multiplying in these in place of the natural rhizobium symbionts. The involved species featured taxa known as human pathogens including: Enterobacter cloacae, Enterobacter kobei, Escherichia vulneris, Pantoea agglomerans and Leclercia adecarboxylata. A direct screening of the phenotypic determinants of virulence using human cultured cells tested positive for the traits of cytotoxicity, vital stain exclusion and adhesion to epithelia. Antibiogram analyses revealed also a complex pattern of multiple antibiotic resistances. The data suggest that legume root nodules can be a site of survival and of active multiplication for populations of mammalian pathogens, which could thus alternate between the target animal and a number of neutral plant hosts. The worldwide distribution of as yet uninvestigated legumes raises the concern that these represent a general niche that could enhance the hazards posed by microorganisms of clinical nature
Legumes of the Sardinia Island: Knowledge on Symbiotic and Endophytic Bacteria and Interactive Software Tool for Plant Species Determination
No full textA meta-analysis was carried out on published literature covering the topic of interactive plant microbiology for botanical species of legumes occurring within the boundary of the Italian island Sardinia, lying between the Tyrrhenian and the western Mediterranean seas. Reports were screened for the description of three types of bacterial occurrences; namely, (a) the nitrogen-fixing symbionts dwelling in root nodules; (b) other bacteria co-hosted in nodules but having the ancillary nature of endophytes; (c) other endophytes isolated from different non-nodular portions of the legume plants. For 105 plant species or subspecies, over a total of 290 valid taxonomical descriptions of bacteria belonging to either one or more of these three categories were found, yielding 85 taxa of symbionts, 142 taxa of endophytes in nodules, and 33 in other plant parts. The most frequent cases were within the Medicago, Trifolium, Lotus, Phaseolus, and Vicia genera, the majority of symbionts belonged to the Rhizobium, Mesorhizobium, Bradyrhizobium, and Sinorhizobium taxa. Both nodular and extra-nodular endophytes were highly represented by Gammaproteobacteria (Pseudomonas, Enterobacter, Pantoea) and Firmicutes (Bacillus, Paenibacillus), along with a surprisingly high diversity of the Actinobacteria genus Micromonospora. The most plant-promiscuous bacteria were Sinorhizobium meliloti as symbiont and Bacillus megaterium as endophyte. In addition to the microbial analyses we introduce a practical user-friendly software tool for plant taxonomy determination working in a Microsoft Excel spreadsheet that we have purposely elaborated for the classification of legume species of Sardinia. Its principle is based on subtractive keys that progressively filter off the plants that do not comply with the observed features, eventually leaving only the name of the specimen under examination
Novel IS elements-based PCR approaches for species identification and strain fingerprinting in rhizobia and other bacteria
No full textAppropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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