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Over 90% of introduced marine species are seaweeds. Seaweeds rely on their microbiome for host settlement, nutrition, development and health. As such, it is likely that microbiomes are involved in seaweed invasions. Sargassum muticum, indigenous to Southeast Asia, inhabits the North-east Atlantic from Norway to Morocco. This is the only known successful case of a non-clonal marine invader with almost no genetic variation over its large NE Atlantic introduced range. This makes it a very interesting model to study an invasive seaweeds microbiome, as it practically uncouples host genetic variation from microbiome variation. Associated bacteria potentially contribute to the plasticity and acclimation of S. muticum leading to its success over the last 50 years. Dispersing host organisms can either bring their acquired microbes along or obtain new ones locally, following the mutualist and generalist host hypothesis, respectively. We used partial 16S rRNA gene amplicon sequencing to characterize the total and core microbiome across S. muticum structures/tissues from five NE Atlantic regions, from Norway to Morocco, covering over 30 degrees of latitude. In contrast to host genotypes, highly diverse, regional, total and core microbiomes, with differentiation levels depending on tissue, bacterial community structure were detected. Atlantic S. muticum follows the generalist host hypothesis, possibly recruiting a new microbiome in each new region. This host promiscuity may promote the invasiveness of S. muticum. Diversity was lower in the young/annual tissues compared with the older tissues for the total bacterial community, suggesting that these are mostly transitory bacteria accumulating over time in the older parts. The total core microbiome included 10 OTUs, representing dominant community members commonly found in other seaweeds' cores. The core Granulosicoccus OTU followed a clear regional pattern where northern and southern regions clustered differentially, suggesting a regional signature even at an OTU level. LA/P/0101/2020 info:eu-repo/semantics/publishedVersion

NAZARÉ, Raphaela Piedade Corrêa - Produção de bioetanol a partir de Sargassum muticum (Phaeophyceae). Coimbra : [S.n.], 2015. Dissertação de Mestrado. Sagarssum muticum é membro da ordem Fucales, da família Sargassaceae, e do gênero Sagarssum. Esta espécie é um potencial competidor e substituto de membros de Laminariales e Fucales que, em suas comunidades, são considerados como espécies chaves ou críticas. As macroalgas têm como um dos seus constituintes predominantes, os polissacarídeos, onde os principais são: alginato, ágar e carragenanas, assim a classe Phaeophyceae, apresenta especial predominância do ácido algínico, que através de hidrólise ácida destaca subprodutos como a glicose, a fucoidana e o ácido algínico, sendo este último um polímero linear que apresenta resíduos do ácido β-D manorônico, assemelhando-se desta forma à pectina e à celulose, que ao sofrerem fermentação permitem a produção de bioetanol. As amostras de Sargassum muticum foram submetidas a extração de polissacarídeos, sacarificação ácida e enzimática, fermentação com S. cerevisiae e analisadas por HPLC e CG para monitoração dos índices de etanol. Os maiores teores de açúcares foram encontradas nas sacarificações realizadas com H2SO4 a 5%, seguida por 2,5% e 3%. Entre os hidrolisados submetidos a fermentações com Saccharomyces cerevisiae, obteve-se os maiores teores de produção de etanol. Já as que apresentaram os menores índices foram as amostras H2SO4 a 4% e as que receberam sacarificação por celulase. O baixo desempenho das fermentações dos hidrolisados com celulase pode ter sido influenciado pela baixa atividade da enzima (1,44U/mg), se comparada com as celulases comercializadas atualmente (atividade igual ou superior a 700 U/mg). Neste trabalho, foram analisadas e contabilizadas por Cromatografia Gasosa, a presença de etanol que mostrou de forma clara resultados compatível com taxa de produção de etanol observada nos hidrolizados com H2SO4 a 2,5% e 4% (variação 2), pois, estes são os únicos a apresentar valores acima de 50%, distanciando-se do percentual dos demais hidrolisados. Sagarssum muticum is member of the Fucales Order, Sargassaceae Family, and Sagarssum Genus. This species is a potential competitor and substitute of the Laminariales and Fucales members that in their communities, they are considered key species or critical. The macroalgae have as one of its predominant constituent, polysaccharides, where the main ones are: alginate, agar and carrageenan. thus the class Phaeophyceae, presents special predominance of alginic acid, which by acid hydrolysis by-products out as glucose, and fucoidana alginic acid, the last being a linear polymer having residues of the β -D manorônico acid, thus resembling the pectin and cellulose that undergo fermentation to allow the production of bioethanol. The samples of the S. muticum were subjected to extraction of polysaccharides, acidic and enzymatic saccharification, fermentation with S. cerevisiae and analysed by HPLC and GC to monitor levels of ethanol. The higher sugar content were found in sacarificações performed with 5 % H2SO4, followed by 2.5% and 3%. Among the hydrolysates subjected to fermentation with Saccharomyces cerevisiae, the highest levels of ethanol production was obtained. Those that had the lowest rates were samples H2SO4 4% and those receiving saccharification by cellulase. The poor performance of fermentation of hydrolyzed with cellulase may have been influenced by the low enzyme activity (1,44U/mg), compared with cellulases currently marketed (activity less than 700U/mg). In this work, the presence of ethanol was recorded and analyzed by gas chromatography, which clearly showed consistent results with ethanol production rate observed in hydrolyzed with H2SO4 2,5% and 4%, because these are the only present values above 50%, away from the percentage of other hydrolysates.