Percorrer por autor "Barbosa, Miguel"
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- Do toxic epiphytic microalgae compromise the consumption of edible macroalgae?Publication . Chainho, Tomás; Cereja, Rui; Barbosa, Miguel; Xavier, Maria João; Pereira, Alícia; Oliveira, Inês; Caria Mendes, Madalena; Marques, António; Reis Costa, PedroThe growing global demand for farmed macroalgae highlights the need to better understand potential contaminant loads, including toxins from harmful algal blooms, and their implications to human health. In this study, the green macroalga Ulva rigida was co-cultivated with the epiphytic dinoflagellate Prorocentrum lima to determine whether toxins produced by the toxic dinoflagellate accumulate in the macroalgae and assess the efficacy of post-harvest processing techniques to reduce or eliminate the risk of toxins contamination. Ulva rigida (60 g wet weight) was maintained under controlled laboratory conditions in sterile F/2 medium and in co-culture with P. lima. Macroalgae were divided into two treatments: a) no processing; b) processing. Samples were analysed by LC-MSMS to detect okadaic acid (OA) and dinophysistoxin-1 (DTX1). High toxins levels were detected after 7 days of exposure to P. lima. Contrastingly, the post-harvesting process of washing and scrubbing was efficient in reducing toxins loads, indicating that lipophilic toxins were surface bound and can be easily eliminated using efficient post-harvest processes. The results indicate that epiphytic toxic microalgae may jeopardize the consumption of macroalgae, particularly if appropriate post-harvest processes are not applied to ensure the safety of farmed macroalgae for consumers.
- Effect of temperature on growth and yessotoxin production of protoceratium reticulatum and lingulodinium polyedra (Dinophyceae) isolates from the Portuguese coast (NE Atlantic)Publication . Barbosa, Miguel; Reis Costa, Pedro; David, Helena; Lage, Sandra; Amorim, AnaThe dinoflagellates Protoceratium reticulatum and Lingulodinium polyedra are potential yessotoxin (YTX) producers, which have been associated with blooms responsible for economic, social, and ecological impacts around the world. They occur in Iberian waters, but in this region, little is known of their ecophysiology and toxin profiles. This study investigated the growth and toxin production of two strains of each species, from the Portuguese coast, at 15 degrees C, 19 degrees C, and 23 degrees C. Growth curves showed higher growth rates at 19 degrees C, for both species. YTX and three analogs (homo YTX; 45-OH YTX; 45-OH homo YTX) were investigated by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS), and the presence of other analogs was investigated by Liquid Chromatography-High-Resolution Mass Spectrometry (LC-HRMS). No evidence of toxin production was found in L. polyedra. By contrast, YTX and 45,55-diOH-YTX were detected in both strains of P. reticulatum. These results confirm P. reticulatum as a source of yessotoxins along the Portuguese coast and add to the observed high intraspecific variability on YTX production of both species, at a global scale.