1,721,038 research outputs found
Application of electronic nose technology for the detection of fungal contamination in library paper
No full textStudies were carried out in vitro on a cellulose based agar at two water activities (a(w),0.975,0.995) and on three types of paper at two relative humidities (75, 100% RH) for the potential for differentiation of contamination and colonisation by Aspergillus terreus, A. holandicus and Eurotium chevalieri. In vitro studies showed that conducting polymer sensor array gave different responses to each of these species when grown on cellulose agar at both a, levels. Discriminant function analyses of the data showed differentiation of the controls from the spoilage fungi. Cluster analysis gave a significant (P = 0.05) separation of the control and each spoilage fungus. In situ studies on three types of paper showed that using natural substrates the volatile patterns produced by each of these fungi was different from each other and from the control. The results obtained were better at the higher humidity. The three paper types could be successfully differentiated into clusters. For a single paper type, differentiation of controls from spoilage fungal treatments was better at the higher humidity. This study has shown that this technology has potential for the early detection of fungal contamination in library materials and archives for the improved protection of cultural heritage. (C) 2004 Elsevier Ltd. All rights reserved
Growth responses to and accumulation of vanadium in agricultural soil fungi
No full textThe aim of this work was to test the growth response of some selected species to toxic metal vanadium, chosen among those isolated from contaminated agricultural soils (organochlorines, potentially toxic elements) in the "Valle Latina" (Lazio, Italy). This area contains high levels of potentially toxic elements due both to human activities and the presence of volcanic rocks (pyroclastic deposits). In particular. vanadium levels exceed the threshold values established by Italian legislation. The soil fungal community was found to be rich in species and we tested the growth responses of six selected species of saprotrophic fungi (Aspergillus terreus, Cladosporium cladosporioides, Clonostachys rosea, Paecilomyces lilacinus, penicillum citrinum, Rhizopus arrhizus). Culture medium (MEA) was amended with ammonium vanadate at concentrations of 1, 2, 3 and 6 mM. Results were based on growth measurements, the tolerance index (TI), scanning electron microscopy (SEM), energy dispersion X-ray microanalysis (EDXA) and the metal concentration in the biomass determined by means of inductively coupled plasma mass spectrometry (ICP-MS). Results revealed a tolerance to vanadium for all the fungi tested at concentrations of up to 6 mM. Tolerance of soil fungi to high natural metal concentrations might be the key factor underlying their tolerance to anthropogenic contamination
Study of tricalcium phosphate solubilization by some soil microfungi and evaluation of their potential as efficient plant growth-promoting organisms for Glycine max
No full textThe potential of use of fungi and bacteria as biological fertilizers is widely recognized and represents a key strategy to improve the phosphorous (P) availability for crops. P is both mobilized and sequestered in soil by the interaction of biological and geochemical processes. Exchangeable P represents a short-term storage pool that can replenish the soil solution. The aims of this research were to study P solubilisation mechanisms of some selected fungal strains with different life strategies and to evaluate their potential to promote efficiently soy growth. Saprotrophic fungi play very important geoactive roles in P biogeochemical cycle, for instance by leaching minerals and solubilizing insoluble P with different mechanisms in soils. The soybean is one of the most important plant for food production worldwide. P depletion is one of the most relevant abiotic constraints that threaten soybean production. Chemical analyses with SEM/EDXA, colorimetric quantification and ICP-MS were performed to quantify TCP solubilised by fungi in liquid medium and P concentration in fungal biomass (1–6). Tested fungi were able to solubilise tricalcium phosphate (TCP) in different extents, increasing P concentration in liquid medium and in biomass. Evaluation of soy growth promotion ability and fungal-plant interactions were studied by microscopy and histological evaluation of seedlings
The extreme environment of a library: Xerophilic fungi inhabiting indoor niches
Full text linkThe use of Compactus shelves by libraries and archives is a good solution to optimize the storage space and prevent dust deposits on books. However, they are probably the cause of severe cases of fungal colonization in historical library materials. A typical phenomenon occurs as a spread of white mycelial growth forming scattered spots, mainly on volumes with leather or fabric bindings. Recent studies have identified the xerophilic fungus Eurotium halophilicum (anamorph Aspergillus halophilicus) as responsible for this kind of contamination. A similar situation was found inside the Library of Humanities (BAUM), at Ca' Foscari University, Venice (Italy). Various sampling methods, including cotton swabs and adhesive tape, were adopted to isolate fungi from books and a set of aerobiological analyses was performed to characterize the environment of the repository. The presence of E. halophilicum on both books and in the indoor air was confirmed by direct observation of adhesive tape samples, microscopic observations and molecular methods. Moreover, Aspergillus creber and Aspergillus protuberus belonging to the revised group Aspergillus section Versicolores, were also isolated for the first time in Italian conservation environments
Fungal contamination specifically related to the use of Compastus shelvings: the case study of a Venetian library
Full text linkHow Peroxisomes Affect Aflatoxin Biosynthesis in Aspergillus Flavus
No full textIn filamentous fungi, peroxisomes are crucial for the primary metabolism and play a pivotal role in the formation of some secondary metabolites. Further, peroxisomes are important site for fatty acids beta-oxidation, the formation of reactive oxygen species and for their scavenging through a complex of antioxidant activities. Oxidative stress is involved in different metabolic events in all organisms and it occurs during oxidative processes within the cell, including peroxisomal beta-oxidation of fatty acids. In Aspergillus flavus, an unbalance towards an hyper-oxidant status into the cell is a prerequisite for the onset of aflatoxin biosynthesis. In our preliminary results, the use of bezafibrate, inducer of both peroxisomal beta-oxidation and peroxisome proliferation in mammals, significantly enhanced the expression of pex11 and foxA and stimulated aflatoxin synthesis in A. flavus. This suggests the existence of a correlation among peroxisome proliferation, fatty acids beta-oxidation and aflatoxin biosynthesis. To investigate this correlation, A. flavus was transformed with a vector containing P33, a gene from Cymbidium ringspot virus able to induce peroxisome proliferation, under the control of the promoter of the Cu, Zn-sod gene of A. flavus. This transcriptional control closely relates the onset of the antioxidant response to ROS increase, with the proliferation of peroxisomes in A. flavus. The AfP33 transformant strain show an up-regulation of lipid metabolism and an higher content of both intracellular ROS and some oxylipins. The combined presence of a higher amount of substrates (fatty acids-derived), an hyper-oxidant cell environment and of hormone-like signals (oxylipins) enhances the synthesis of aflatoxins in the AfP33 strain. The results obtained demonstrated a close link between peroxisome metabolism and aflatoxin synthesis
Metabolic profiling of Minimedusa polyspora (Hotson) Weresub & P.M. LeClair, a cellulolytic fungus isolated from Mediterranean maquis, in southern Italy
No full textThe fungus Minimedusa polyspora (Hotson) Weresub & P.M. Le Clair was isolated during a survey aimed at collecting cellulolytic fungi from the soil-litter interface of the Mediterranean maquis environment in Italy. The metabolic profiling of the species and its ability to translocate nutrients between decaying leaf litter and soil have been investigated by means of Phenotype MicroArray (TM), Scanning Electron Microscopy and microanalysis techniques. The Phenotype MicroArray (TM) showed that the fungus possesses a preference for polysaccharides at the initial phases of its growth, and that it prefers hexoses and then oligosaccharides in the later phases of its development. M. polyspora proved to be capable of concentrating several important biogenic microelements (N, P, S, K and Ca), which are absent in the cellulosic substrate before fungal colonization. This capacity for nutrient uptake and translocation from other sources than cellulose makes this fungus a very efficient pioneer colonizer that requires little nitrogen, is fast growing, changes its own metabolism according to the early modifications of the substrate and uses inhibitory substances to make the habitat unfavourable for other species
Analytical evaluation of gelatin removal from ancient papers induced by wet cleaning: a comparison between immersion treatment and application of rigid Gellan gum
No full textIn paper conservation, wet cleaning treatments are usually performed to remove harmful degradation substances. Although cleaning treatments are fundamental in this field, the use of free water, besides causing an excessive swelling of cellulose fibres and sometimes also strong alterations of graphic media, could induce the extraction of the original sizing agents, resulting in a weakening of the paper structure. Rigid polysaccharide hydrogels (i.e. Gellan gum) can be effectively used to minimize the impact of water on paper. The present study evaluates the rate of gelatine removal from paper artworks comparing two different wet cleaning treatments: washing by immersion in free deionised water and by means of Gellan gum application. After a preliminary characterization of the paper samples through Hertzberg stain test and Fourier Transform Infrared Spectroscopy (FT-IR), the study is carried out using Gas Chromatography - Mass Spectrometry analysis (GC-MS). The results showed that Gellan gum was less invasive than immersion treatment since it caused the extraction of lower amounts of gelatine from paper. The gelatine removal was also tested by statistical analysis, in particular Principal Component Analysis (PCA) of amino acids
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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