Browsing by Author "Tamagnini, Paula"
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- Extracellular proteins: Novel Key components of metal resistance in cyanobacteria?Publication . Joaquín, Giner-Lamia; Pereira, Sara B.; Bovea-Marco, Miquel; Futschik, Matthias E.; Tamagnini, Paula; Oliveira, PauloMetals are essential for all living organisms and required for fundamental biochemical processes. However, when in excess, metals can turn into highly-toxic agents able to disrupt cell membranes, alter enzymatic activities, and damage DNA. Metal concentrations are therefore tightly controlled inside cells, particularly in cyanobacteria. Cyanobacteria are ecologically relevant prokaryotes that perform oxygenic photosynthesis and can be found in many different marine and freshwater ecosystems, including environments contaminated with heavy metals. As their photosynthetic machinery imposes high demands for metals, homeostasis of these micronutrients has been widely studied in cyanobacteria. So far, most studies have focused on how cells are capable of controlling their internal metal pools, with a strong bias toward the analysis of intracellular processes. Ultrastructure, modulation of physiology, dynamic changes in transcription and protein levels have been studied, but what takes place in the extracellular environment when cells are exposed to an unbalanced metal availability remains largely unknown. The interest in studying the subset of proteins present in the extracellular space has only recently begun and the identification and functional analysis of the cyanobacterial exoproteomes are just emerging. Remarkably, metal-related proteins such as the copper-chaperone CopM or the iron-binding protein FutA2 have already been identified outside the cell. With this perspective, we aim to raise the awareness that metal-resistance mechanisms are not yet fully known and hope to motivate future studies assessing the role of extracellular proteins on bacterial metal homeostasis, with a special focus on cyanobacteria.
- Pilot scale production of Crocosphaera chwakensis CCY0110 and evaluation of its biomass nutritional potentialPublication . Matinha-Cardoso, Jorge; Santos, Tamara; Pereira, Hugo; Varela, João; Tamagnini, Paula; Mota, RitaIn recent years, the large-scale cultivation and commercialization of microalgae/cyanobacteria biomasses have become a worldwide trend, mainly directed to the animal and human nutrition markets due to their outstanding nutritional value. However, only a very limited number are currently classified as food ingredients by Food Safety regulators worldwide. Crocosphaera chwakensis CCY0110 is a marine unicellular cyanobacterium that produces a promising and versatile extracellular carbohydrate polymer (Cyanoflan). Therefore, envisaging a biorefinery approach with a multi-product stream (zero-waste), C. chwakensis biomass was for the first time cultivated at pilot-scale in a 120 L flat panel photobioreactor and its nutritional composition was evaluated. The results obtained revealed high protein and fat-soluble vitamins content (similar to 54 g of protein, 6 mg vitamin A and 25 mg vitamin E per 100 g biomass dry weight), coupled with a balanced amount of essential amino acids and n-3 polyunsaturated fatty acids (36 % of total fatty acids). Moreover, C. chwakensis biomass can also be considered as a great source of important minerals, such as potassium (3 g per 100 g DW), magnesium (0.5 g per 100 g DW) and iron (95 mg per 100 g DW), as well as phycocyanin, a high-value blue pigment with a wide array of applications. Overall, C. chwakensis biomass displays a nutritional composition that outdo traditional feedstocks and competes with already established and commercially available cyanobacteria and microalgae. This work highlights the potential of C. chwakensis as a multi-product cyanobacterium for blue bioeconomy, combining the production of a promising biopolymer with biomass valorization.