Probing biodiversity of microalgal productivity in environmental photobioreactor simulations

CORONEL, CAMILA D.; DO NASCIMENTO, MAURO; CURATTI, LEONARDO

San Luis

Congreso; XIII Congreso Argentino De Microbiología General SAMIGE; 2018

Asociación Civil de Microbiología General

Increasing demand for energy and substantial reduction of unsustainable sources like fossil fuels have led to look forward towards renewable resources. First generation of biofuels is one of such alternatives and is produced from edible plant crops. The most advanced generation of biofuels (third generation) is proposed to be obtained from photosynthetic microbes, like microalgae, in non-arable lands. However, commercialization of these biofuels is currently very limited mostly due to high production costs. While algal culture in open ponds demands lower capital investments, productivity, especially under winter conditions, normally off-sets profitability. Bioprospecting for native microalgae for desirable traits is a very useful strategy and more broadly accepted than genetic engineering towards strains optimization for increased productivity.Thus, we started some bioprospecting studies from two contrasting eco-region from Argentina: South eastern Buenos Aires and La Quiaca, Jujuy. The most contrasting weather parameter was maximum irradiation during autumn. La Quiaca?s irradiance is among the highest in the planet. We gathered two microalgae strains collections of about 25 entries for each site. Strains were domesticated and identified by morphological and molecular taxonomy. Biochemical analysis of the biomass was performed under N-deficiency to trigger lipid or carbohydrate reserves accumulation. Two pairs of strains, one from each contrasting site were selected as very closely related strains, at the rDNA sequence, but isolated from regions of contrasting irradiance. Biomass productivity and biochemical composition did not change under laboratory culture conditions at low or high irradiance. However, productivity simulations in environmental photobioreactors mimicking cultivation in open ponds under Buenos Aires or La Quiaca average weather conditions suggested that a Scenedesmus obliquus strain (C1S) from Buenos Aires presented a higher productivity under Buenos Aires autumn conditions than the La Quiaca?s S. obliquus strain (P5). Furthermore, the Buenos Aires strain was even more productive under La Quiaca?s average weather conditions in the same season. However, under simulated weather of La Quiaca of a fully shiny month at 20 cm deep ponds, and especially under 5 cm ponds both strains tend to attain similar and high productivities.Overall, light appears as one of the main limitations for algal productivity and the case study of these S. obiquus strains suggested that strains naturally acclimated to lower irradiances might be broadly more productive in deeper open ponds for an increased areal productivity.These are pioneering simulations and geographical comparisons of microalgal productivity under environmental conditions in South America and would be very useful for the development of algal biotechnology in the region.