ESTM - Mestrado em Biotecnologia dos Recursos Marinhos
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Browsing ESTM - Mestrado em Biotecnologia dos Recursos Marinhos by Author "Batista, Daniela Marina Antunes"
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- Seaweed potencial to fight Erwinia amylovora, the causal agent of fire blightPublication . Batista, Daniela Marina Antunes; Lemos, Marco Filipe Loureiro; Félix, Carina Rafaela Faria da Costa; Novais, Sara CalçadaOne of the primary challenges that agriculture faces is the significant loss of food caused by microbial diseases, which can devastate entire crops, leading to a substantial reduction in crop yields and decreased economic profits. Approximately 16% of crop losses are attributed to phytopathogens, resulting in food shortages, malnutrition, poverty, and broader societal issues. Fire blight, a disease caused by the bacterium Erwinia amylovora, has been responsible for the destruction of pear and apple orchards and other crops worldwide, leading to a considerable decline in production and significant economic losses. Currently, effective methods to control this disease are lacking, as the available products, primarily antibiotics and copper-based compounds, have been banned or highly restricted in the European Union due to their negative environmental and human health impacts. Hence, it is crucial to find more sustainable and safer alternatives that are effective against this disease. Seaweeds have long exhibited substantial antimicrobial properties against a wide range of microorganisms. In Portugal, a country with an extensive coastline, there is a significant diversity of seaweeds, both native and invasive, making these organisms excellent candidates for the search of bioactive compounds capable of inhibiting the growth of E. amylovora. Therefore, this study aimed to isolate a virulent strain of E. amylovora from pear trees and assess the antimicrobial potential and mechanisms of action of seaweed extracts from Asparagopsis armata, Sargassum muticum, Fucus vesiculosus, and Codium sp. Twenty extracts were tested at 3 different concentrations. The most notable result obtained in the antimicrobial screening was achieved for the ethanolic extract of A. armata, which demonstrated a growth inhibition of E. amylovora of 97% at 1mg.mL-1. Taking this promising result in consideration, this A. armata extract was selected to further understand its mechanistic effects on biofilm and amylovoran production and swarming motility, three relevant mechanisms associated with the pathogenesis of this bacterium. It was possible to observe that the ethanolic extract of A. armata did not inhibit the biofilm formation, but the amylovoran production was mostly reduced in the presence of low concentrations, such as 0.1 mg.mL-1. Regarding the swarming motility assay, higher concentrations (0.5 and 1 mg.mL-1) showed a capacity to avoid the adherence of the bacteria to solid medium. This behaviour of E. amylovora in the presence of extract may be associated to several compounds found in the extract, known to have antibacterial properties, such as 3-bromohexadecanoic acid and monogalactosyldiacylglycerol, among other compounds known for their relevant activity as antimicrobials.