2 resultados para Aspergillus niger
em AMS Tesi di Dottorato - Alm@DL - Università di Bologna
Resumo:
Aflatoxin (AFL) contamination of corn is a serious economic and food security issue. Although a variety of technical solutions for reducing AFL contamination of corn have been proposed, only a few have produced satisfactory results. A successful approach is a biocontrol strategy consisting of using non-flatoxigenic strains of Aspergillus flavus to replace indigenous AFL-producing isolates. The main objective of the present thesis was to investigate the dynamic and contamination of AFL/A. flavus in corn in Northern Italy. The study also investigated the role of the key-pest of corn, the European Corn Borer (ECB), on AFL contamination and dispersal of A. flavus propagules in corn. Finally, the study evaluated the feasibility of bioplastic-based granules entrapping a non-aflatoxigenic A. flavus strain for the biocontrol of this fungus in corn. The 2-year field study demonstrated the efficacy of the bioplastic formulation to reduce AFL contamination in corn. More precisely, although AFL contamination varied among the two years, application of 15 and 30 kg ha-1 of granules reduced AFL contamination to up 60 and 85% in 2009 and 2010 respectively. Microbiological analysis showed that the relative abundance of non-aflatoxigenic soil isolates significantly increased after 1 month from granules application (mid-May) and throughout the corn-growing season. These findings were consistent with data obtained using a bioplastic-based bait specifically developed to selectively isolate Aspergilli from soil and other environmental samples. In addition, field and laboratory evaluations showed that the level of damages produced by ECB larvae were not significantly correlated to A. flavus infestation and AFL contamination. Taking together, these findings demonstrated that AFL contamination of corn in Northern Italy was variable, but above the EU limit for human consumption. First proposed in the USA, this study showed the practical possibility of this formulation to be use for reducing AFL contamination in corn in the EU.
Resumo:
Development aid involves a complex network of numerous and extremely heterogeneous actors. Nevertheless, all actors seem to speak the same ‘development jargon’ and to display a congruence that extends from the donor over the professional consultant to the village chief. And although the ideas about what counts as ‘good’ and ‘bad’ aid have constantly changed over time —with new paradigms and policies sprouting every few years— the apparent congruence between actors more or less remains unchanged. How can this be explained? Is it a strategy of all actors to get into the pocket of the donor, or are the social dynamics in development aid more complex? When a new development paradigm appears, where does it come from and how does it gain support? Is this support really homogeneous? To answer the questions, a multi-sited ethnography was conducted in the sector of water-related development aid, with a focus on 3 paradigms that are currently hegemonic in this sector: Integrated Water Resources Management, Capacity Building, and Adaptation to Climate Change. The sites of inquiry were: the headquarters of a multilateral organization, the headquarters of a development NGO, and the Inner Niger Delta in Mali. The research shows that paradigm shifts do not happen overnight but that new paradigms have long lines of descent. Moreover, they require a lot of work from actors in order to become hegemonic; the actors need to create a tight network of support. Each actor, however, interprets the paradigms in a slightly different way, depending on the position in the network. They implant their own interests in their interpretation of the paradigm (the actors ‘translate’ their interests), regardless of whether they constitute the donor, a mediator, or the aid recipient. These translations are necessary to cement and reproduce the network.