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Approcci innovativi e sostenibili per il controllo delle malattie fungine dei prodotti ortofrutticoli
No full textLa gestione post-raccolta dei frutti è un punto fondamentale per la filiera produttiva, poiché rappresenta l’ultimo passaggio della catena produttiva prima della commercializzazione. Eventuali contaminazioni, di natura chimica e microbiologica in tale fase, oltre ad affliggere direttamente la salute del consumatore, causano ingenti danni di tipo economico. I frutti sono suscettibili a molte malattie fungine post-raccolta come quelle causate da Botrytis cinerea, Penicillium spp. e Monilinia spp. Tra le possibili strategie di controllo, l'uso di agenti di biocontrollo (BCAs, biocontrol agents) risulta una delle più promettenti. Il lievito Aureobasidium pullulans è un buon candidato grazie, in particolar modo, alla sua elevata tolleranza agli stress e alla capacità di sopravvivere in condizioni estreme. Ceppi di A. pullulans sono stati isolati durante la stagione invernale e caratterizzati molecolarmente, con l'obiettivo di trovare antagonisti attivi da utilizzare durante la conservazione della frutta. Sono stati caratterizzati 38 ceppi e solo due (UC14 e AL25) sono stati selezionati per la loro notevole attività antagonista nei confronti di uno dei principali patogeni fungini post-raccolta delle drupacee, Monilinia fructicola. Il ceppo UC14 è stato successivamente valutato contro Penicillium expansum, noto patogeno delle mele. Il ceppo ha confermato, durante la sperimentazione, il suo potenziale antagonista come BCA, in particolare grazie alla persistenza rilevata durante la lunga conservazione e alla sua capacità di ridurre l'accumulo di patulina. Per un efficace utilizzo dei BCA, la formulazione ne rappresenta il passo fondamentale, pertanto, una parte importante di questa tesi è stata dedicata allo sviluppo. Il ceppo AP1 è stato utilizzato come principio attivo di due tipologie di formulazione (wettable powder, WP e oil dispersion, OD), sviluppate in collaborazione con un'azienda partner. La valutazione dei prodotti ottenuti ha dimostrato alcuni limiti di efficacia solo nella formulazione WP. La formulazione OD, avente come principio attivo AP1, è risultata la più efficace nel controllo dei patogeni in pre- e post-raccolta come Rhizoctonia solani e B. cinerea. L'ampio spettro d'azione di un formulato è la principale caratteristica auspicata di tali prodotti, perciò, i prototipi sviluppati sono stati testati in diverse condizioni e su diversi ospiti, come lattuga e uva da tavola. Nel caso studio su lattuga, oltre all’utilizzo di formulazioni contenente un singolo ceppo, è stato verificato l’effetto stimolante su pianta di un estratto acquoso a base di scarti di coltivazione di Agaricus bisporus.
Oltre ad essere un buon BCA, A. pullulans è anche un ottimo produttore di pullulano, un polimero con eccellenti proprietà tecnologiche e riconosciuto come GRAS. Per questo motivo, una selezione di ceppi di A. pullulans è stata saggiata per verificare la sua capacità produttiva di tale polimero. Le macromolecole ottenute sono state successivamente caratterizzate mediante analisi chimiche (NMR, FT-IT e DSC) e valutate per un successivo utilizzo come rivestimento commestibile su frutta. In particolare, è stata verificate l'efficacia del pullulano ottenuto nei confronti di Colletotrichum acutatum. I risultati ottenuti aprono così nuovi ed interessanti spunti di ricerca come lo sviluppo di nuove formulazioni, metodi di applicazione e utilizzi dei BCA.Postharvest management of fruit is an importan point for the production chain, as it is the last step in the production chain before commercialization. Chemical and microbiological contaminations, at this stage, can directly affect the health of the consumer, and also cause significant economic losses. Fruits are susceptible to many postharvest fungal diseases such as those caused by Botrytis cinerea, Penicillium spp. and Monilinia spp. Among the possible control strategies, the use of biocontrol agents (BCAs) appears to be one of the most promising. The yeast-like fungus Aureobasidium pullulans is a good candidate, especially due to its high stress tolerance and ability to survive under extreme conditions. Strains of A. pullulans were isolated during the winter season and molecularly characterized, with the goal of finding active antagonists to use during fruit storage. Thirty-eight strains were characterized, and only two (UC14 and AL25) were selected for their remarkable antagonistic activity against one of the major postharvest fungal pathogens of stone fruit, Monilinia fructicola. Strain UC14 was subsequently evaluated against Penicillium expansum, a known pathogen of apples
The strain confirmed, during the research, its potential as BCA, particularly due to its persistence during the long storage and its ability to reduce patulin accumulation. For an effective use of BCAs, the formulation is the key step; therefore, an important part of this thesis was dedicated to its development. AP1 strain, weas used as active ingredients of two types of formulations (wettable powder, WP, and oil dispersion, OD), developed in collaboration with a partner company. The evaluation of the obtained products showed some efficacy limitations in the WP formulation. Instead, the OD formulation, having AP1 as active ingredient, was found to be the most effective in controlling pathogens in pre- and post-harvest conditions, such as Rhizoctonia solani and B. cinerea. The broad spectrum of action of a formulation is the main desired feature of such products, and therefore the developed prototypes were tested under different conditions and on different hosts, such as lettuce and table grapes. On lettuce, in addition to the use of formulations containing a single strain cells, the growth promoting effects on plants of aqueous extracts based on Agaricus bisporus wastes was tested.
In addition to being a good BCA, A. pullulans is also an excellent producer of pullulan, a polymer with excellent technological properties and recognized as GRAS. For this reason, different A. pullulans strains were assayed to verify their ability to produce this polymer. The macromolecules obtained were subsequently characterized by chemical analysis (NMR, FT-IR, and DSC) and evaluated for subsequent use as edible coating on fruit. In particular, the efficacy of the obtained pullulan coatings against Colletotrichum acutatum was verified. The obtained results open up new and interesting research perspectives such as the development of new formulations, application methods and uses of BCAs
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
First Report of Neopestalotiopsis clavispora Causing Grapevine Trunk Disease in Northeastern Italy
No full textVariations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Aspects of the biocontrol activity of Aureobasidium spp. strain against Penicillium expansum of apple
No full textEffects of bioformulation prototype and bioactive extracts from Agaricus bisporus spent mushroom substrate on controlling Rhizoctonia solani of Lactuca sativa L
Get PDFIntroductionFood security and waste management represent the main challenges that need to be addressed in the near future. The use of bioformulations and bioactive compounds obtained from agricultural wastes could represent some of the solutions for the management of soil-borne pathogens.MethodsIn the present study, Aureobasidium pullulans strain AP1, tested in oil dispersion (OD) formulation prototype and bio-extracts [hot water extract (HWE) and warm water extract (WWE)] derived from spent mushroom substrate (SMS) of Agaricus bisporus, was tested as sustainable strategies to manage Rhizoctonia solani of lettuce.ResultsBy in vitro assays, AP1OD at 600 mg L−1 displayed an inhibition by 57% of pathogen mycelial growth, and the SMS extract WWE (40°C) showed a growth stimulation of lettuce seedling by 27%. By In vivo assays, AP1OD formulation used against R. solani reduced by 66.6% the soil-borne pathogen incidence on lettuce plants, and both bio-extracts significantly stimulated lettuce leaves and roots growth (>200%). AP1OD formulation and HWE treatments increased the lettuce genes expression levels (ggps and hppd pdx1) mainly imputed to plant antioxidant potential, vitamin E, and vitamin B6 biosynthesis.DiscussionThe present study reported the potential of a new formulation and two bio-extracts, derived from an agricultural waste, to use against R. solani of lettuce, respectively, with antifungal and biostimulant properties
Aureobasidium pullulans formulations: evaluation of the effectiveness against grey mould of table grape
Get PDFDispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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