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- Symbiotic co-culture of Scenedesmus sp. and Azospirillum brasilense on N-deficient media with biomass production for biofuelsPublication . Contreras, José R.; Mata, Teresa M.; Cuellar-Bermudez, Sara P.; Caetano, Nídia S.; Chandra, Rashmi; Garcia-Perez, J. Saul; Muylaert, Koenraad; Parra-Saldivar, RobertoThe treatment of nitrogen-deficient agriculture wastewater, arising from the vegetable and fruit processing, is a significant problem that limits the efficiency of its biological treatment. This study evaluates the effectiveness of the symbiotic co-culture of Azospirillum brasilense and Scenedesmus sp., under two nitrogen levels (8.23 mg L−1 and 41.17 mg L−1) and mixing systems (aeration and magnetic stirring), aiming to simultaneously use the N-deficient media for their growth while producing biomass for biofuels. Microalgae growth and biomass composition, in terms of protein, carbohydrate and fatty acid contents, were evaluated at the end of the exponential growth phase (15 days after inoculation). Results show that the symbiotic co-culture of microalgae-bacteria can be effectively performed on nitrogen-deficient media and has the potential to enhance microalgae colony size and the fatty acid content of biomass for biofuels. The highest biomass concentration (103 ± 2 mg·L−1) was obtained under aeration, with low nitrogen concentration, in the presence of A. brasilense. In particular, aeration contributed to, on average, a higher fatty acid content (48 ± 7% dry weight (DW)) and higher colony size (164 ± 21 µm2) than mechanical stirring (with 39 ± 2% DW and 134 ± 21 µm2, respectively) because aeration contribute to better mass transfer of gases in the culture. Also, co-culturing contributed in average, to higher colony size (155 ± 21 µm2) than without A. brasilense (143 ± 21 µm2). Moreover, using nitrogen deficient wastewater as the culture media can contribute to decrease nitrogen and energy inputs. Additionally, A. brasilense is approved and already extensively used in agriculture and wastewater treatment, without known environmental or health issues, simplifying the biomass processing for the desired application.
- Microalgae for pigments and cosmeticsPublication . Caetano, Nídia S.; Corrêa, Priscila S.; Morais Júnior, Wilson G. de; Oliveira, Gisela M.; Martins, Antonio A.A.; Branco-Vieira, Monique; Mata, Teresa M.Microalgae are among the most promising cell factories of the near future. Their renewable nature, and ability to rely on photosynthesis to use CO2 or nutrients from wastewater to grow and multiply, make them an emergent source of valuable natural compounds. Although in the past, a few of these microalgae have been known for their value as a source of proteins, carbohydrates, exopolysaccharides, polyunsaturated fatty acids, omega 3 and omega 6 fatty acids, recently they have also been found increasingly important sources of more valuable compounds such as carotenoids, of which astaxanthin, lutein and β-carotene are of extreme importance in food, feed and cosmeceutical industries, and phycobiliproteins, chlorophylls, that are finding their place in the commercial market. There are still various challenges to be addressed to make sustainable the production of some of these valuable bioproducts. However, the circular economy and the biorefinery approach are at the center of the whole process to make the microalgae-based industry one of the most dynamic, modern and profitable industries. In this chapter it will be presented the potential microalgae sources of these valuable compounds, existing industrial applications, as well as the major ongoing research projects, and their contribution driving the blue bioeconomy.