UV-A promotes long-term carotenoid production of Dunaliella in photobioreactors with retention of cell viability

The effect of adding UV-A radiations (320-400 nm) to photosynthetically active radiation (PAR, 400-700 nm) during the growth of Dunaliella bardawil in an air-fluidized bed photobioreactor was studied to evaluate cell growth and long-term production of carotenoids. The obtained results were compared to those obtained from D. bardawil cultures incubated under lab standard conditions for carotenoid production, this is to say, nitrogen starvation and absence of UV-A radiation. The addition of 26.5 μmol photons m-2 s-1 UV-A radiation to 1150 μmol photons m-2 s-1 PAR stimulated the growth of D. bardawil cultures grown in a full nutrient culture medium. The total carotenoid content, mostly β-carotene, was higher than that of control cultures (UV-A non added cultures) along the exponential phase. The concentration of β-carotene in UV-A added cultures after 450 h was found to be about two-fold that of control cultures. From the results of this work it can be concluded that the UV-A modulated addition to PAR could be successfully applied to long-term carotenoid production processes, whereas D. bardawil cells accumulates carotenoids with retention of its viability. It is also shown that UV-A promotes increases of both carotenoid production per culture volume unit and the specific carotenoid production rate (pg.cell-1), β-carotene being the major accumulated carotenoid

β-Carotene production enhancement by UV-A radiation in Dunaliella bardawil cultivated in laboratory reactors

β-carotene is an antioxidant molecule of commercial value that can be naturally produced by certain microalgae that mostly belong to the genus Dunaliella. So far, nitrogen starvation has been the most efficient condition for enhancing β-carotene accumulation in Dunaliella. However, while nitrogen starvation promotes β-carotene accumulation, the cells become non-viable; consequently under such conditions, continuous β-carotene production is limited to less than 1 week. In this study, the use of UV-A radiation as a tool to enhance long-term β-carotene production in Dunaliella bardawil cultures was investigated. The effect of UV-A radiation (320–400 nm) added to photosynthetically active radiation (PAR, 400–700 nm) on growth and carotenoid accumulation of D. bardawil in a laboratory air-fluidized bed photobioreactor was studied. The results were compared with those from D. bardawil control cultures incubated with PAR only. The addition of 8.7 W .m−2 UV-A radiation to 250W .m−2 PAR stimulated long-term growth of D. bardawil. Throughout the exponential growth period the UV-A irradiated cultures showed enhanced carotenoid accumulation, mostly as β-carotene. After 24 days, the concentration of β-carotene in UV-A irradiated cultures was approximately two times that of control cultures. Analysis revealed that UV-A clearly induced major accumulation of all-trans β-carotene. In N-starved culture media, β-carotene biosynthesis in UV-A irradiated cultures was stimulated. We conclude that the addition of UV-A to PAR enhances carotenoid production processes, specifically all-trans β-carotene, in D. bardawil cells without negative effects on cell growth

Microalgas: alimentación, salud y biocombustibles

A Teoria das Representações Sociais (TRS) começou a ser conhecida e divulgada no Brasil principalmente a partir de 1990 no âmbito da Psicologia Social, configurando um movimento que coincidiu com o aumento das preocupações de segmentos da sociedade brasileira com as questões ambientais e a defesa de tese de Reigota no campo da Educação, que articulava essas tendências. Com a publicação dos dois primeiros livros desse autor, a TRS se tornou uma opção às pesquisas em educação ambiental. A aproximação da teoria aos Estudos Culturais, bem como à pedagogia freireana e à pós-moderna, possibilitou a fundamentação de outros trabalhos. Um deles, que originou este artigo, trata da contribuição do sentido político e pedagógico da trajetória e obra de Frans Krajcberg à educação ambiental, enfatizada nas narrativas escritas por componentes do grupo de pesquisa "Perspectiva Ecologista de Educação", da Universidade de Sorocaba, após o encontro com a obra do artista em Curitiba

Outdoor Large-Scale Cultivation of the Acidophilic Microalga Coccomyxa onubensis in a Vertical Close Photobioreactor for Lutein Production

The large-scale biomass production is an essential step in the biotechnological applications of microalgae. Coccomyxa onubensis is an acidophilic microalga isolated from the highly acidic waters of Río Tinto (province of Huelva, Spain) and has been shown to accumulate a high concentration of lutein (9.7 mg g-1dw), a valuable antioxidant, when grown at laboratory-scale. A productivity of 0.14 g L-1 d-1 was obtained by growing the microalga under outdoor conditions in an 800 L tubular photobioreactor. The results show a stable biomass production for at least one month and with a lutein content of 10 mg g-1dw, at pH values in the range 2.5–3.0 and temperature in the range 10–25 ºC. Culture density, temperature, and CO2 availability in highly acidic medium are rate-limiting conditions for the microalgal growth. These aspects are discussed in this paper in order to improve the outdoor culture conditions for competitive applications of C. onubensis.Authors want to thank the PhD-Grant (2015/7949) from CEIMAR (Marine International Campus of Excellence, Spain) to Juan Luis Fuentes