Current rates of CO2 emissions into the atmosphere are causing severe impacts on the planet. To reduce, or at least stabilize, CO2 concentrations in the atmosphere technological solutions will be needed, such as enhancing biological C-fixation, thus capturing and storing CO2. Following this premise, the capture of carbon content in flue gas emissions (one important anthropogenic source of CO2) would contribute to the decrease of this gas in the atmosphere.In this study we have tested the potential of microalgae to use CO2 from flue gas as source of carbon to produce biomass. We evaluated the growth of four microalgal cultures during direct injection of flue gas. We used both freshwater and marine microalgal cultures. We observed that the four microalgae tested were able to grow using this source of carbon, and that although pH of the cultures decreased in the first hour of flue gas addition, it did not reach inhibitory growth levels. These results show the potential of utilizing this kind of technology to both reduce CO2 emissions, and, at the same time, to produce green biomass with many biotechnological applications. Besides, the use of flue gas as source of carbon makes the whole cultivation process cheaper, contributing to the development of viable, sustainable culturing techniques to the production of microalgae biomass.

Abstract:The interaction between live organisms and nanosized particles has become a current focus in toxicology. The aims of the present work are: (i) to assess the zinc oxide (ZnO) toxicity and its mechanisms into the aquatic environment, using the green algae Chlorella vulgaris as biological indicator; (ii) to compare the ZnO behavior and toxic profile in synthetic (Bold's Basal) and natural (Seine River Water, SRW) culture media; and (iii) to address whether the obtaining route is an issue in ZnO particles toxicity or not. Responses such as growth inhibition, cell viability, superoxide dismutase (SOD) activity, adenosine-5-triphosphate (ATP) content and photosynthetic efficiency were evaluated. The main conclusions are: (i) nanoparticulate ZnO have an statistically significant toxic effect on C. vulgaris growth since the lower concentration tested (1ppm), that seems to be mediated by a induced oxidative stress (probably due to extensive release of Zn 2+ into the media); (ii) the ZnO behavior in synthetic and natural culture media were statistically similar, although the toxic effects were more pronounced in SRW; and (iii) the production process does not seem to be an issue in ZnO nanoparticles toxicity since all tested particles produced significant effects on microalgae growth