Cyanobacterial extracellular polymeric substances (EPS) are heteropolysaccharides that possess characteristics suitable for industrial applications, notably a high number of different monomers, strong anionic nature and high hydrophobicity. However, systematic studies that unveil the conditions influencing EPS synthesis and/or its characteristics are mandatory. In this work, Cyanothece sp. CCY 0110 was used as model organism. Our results revealed that this strain is among the most efficient EPS producers, and that the amount of RPS (released polysaccharides) is mainly related to the number of cells, rather than to the amount produced by each cell. Light was the key parameter, with high light intensity enhancing significantly RPS production (reaching 1.8 g L(-1)), especially in the presence of combined nitrogen. The data showed that RPS are composed by nine different monosaccharides (including two uronic acids), the presence of sulfate groups and peptides, and that the polymer is remarkably thermostable and amorphous in nature.

Many cyanobacteria produce extracellular polymeric substances (EPS) with particular characteristics (e.g. anionic nature and presence of sulfate) that make them suitable for industrial processes such as bioremediation of heavy metals or thickening, suspending or emulsifying agents. Nevertheless, their biosynthetic pathway(s) are still largely unknown, limiting their utilization. In this work, a phylum-wide analysis of genes/proteins putatively involved in the assembly and export of EPS in cyanobacteria was performed. Our results demonstrated that most strains harbor genes encoding proteins related to the three main pathways: Wzy-, ABC transporter-, and Synthase-dependent, but often not the complete set defining one pathway. Multiple gene copies are mainly correlated to larger genomes, and the strains with reduced genomes (e.g. the clade of marine unicellular Synechococcus and Prochlorococcus), seem to have lost most of the EPS-related genes. Overall, the distribution of the different genes/proteins within the cyanobacteria phylum raises the hypothesis that cyanobacterial EPS production may not strictly follow one of the pathways previously characterized. Moreover, for the proteins involved in EPS polymerization, amino acid patterns were defined and validated constituting a novel and robust tool to identify proteins with similar functions and giving a first insight to which polymer biosynthesis they are related to.

The blackspot seabream, Pagellus bogaraveo, is a sparid fish of great economic importance in the northeast Atlantic. The main aim of this work was to assess the infection levels and diversity of anisakid nematodes parasitizing P. bogaraveo from Portuguese waters. The anisakid larvae were identified by polymerase chain reaction-restriction fragment length polymorphism analysis and ten different patterns were observed, four of which were not previously reported in the literature. Moreover, several species were detected for the first time in this host: Anisakis simplex × Anisakis pegreffii hybrids, Anisakis ziphidarum, Anisakis typica, Anisakis physeteris, as well as three undescribed anisakids Anisakis sp. PB-2009, Anisakis sp. PB-2010, and Contracaecum sp. PB-2010. The ITS1-5.8S-ITS2 region was sequenced and analyzed phylogenetically, revealing that our anisakids were distributed by the two distinct clades reported previously, corresponding to the two recognized larval morphotypes. Moreover, a group of organisms, including our specimens from Madeira and the previously reported Anisakis sp. HC-2005, cluster together and seem to belong to clade I. A certain degree of intraspecific diversity was also detected. Samples from mainland waters had the highest infection levels and were dominated by A. pegreffii. Madeira had the highest diversity overall, dominated by Anisakis sp. PB-2010. Fish from the Azores had the lowest infection levels, and the species with the highest relative abundance was A. physeteris. The anisakid nematode communities were relatively similar in mainland waters but very distinct in both the Azores and Madeira islands, suggesting the existence of at least three different stocks of P. bogaraveo in the northeast Atlantic.

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