It is generally assumed that increased microalgal biomass productivity on any particular geographical site would be most likely achieved by strains native to that region. However, direct assessment of that hypothesis remains challenging. Here we isolated and biochemically characterized twenty-six microalgal strains from one of the regions with the highest irradiances of the planet. Biomass and lipids productivity of phylogenetically-close Scenedesmus strains native to regions of contrasting irradiances performed similarly under laboratory culture conditions. Culture simulations in environmental photobioreactors, mimicking regional weather conditions, broadly showed physiological responses of these strains according to their origin. However, under the mean weather conditions of a predicted highly productive region, an exotic strain from a lower irradiance zone resulted 40% more productive than a phylogenetically close-relative native strain. These results challenge the generalized view of the convenience of using native microalgae to increase productivity and broadens the discussion towards alternative scenarios.

Microalgal biomass is increasingly considered a promising feedstock for the production of bioethanol because it has simpler biochemical composition and structural features than plant feedstocks. However, it still requires hazardous and/or expensive acid or enzymatic saccharification processes before its conversion into ethanol by fermentation. To bypass this limitation, we identified microalgal strains that accumulate up to 10% (w/w) of sucrose, a readily fermentable sugar. Conditions were optimized to produce sucrose in half-strength seawater, as well as efficient extraction by very mild procedures, and conversion into ethanol. We present a model based on cultivation in environmental photobioreactors that predicted a productivity of 4200 L ethanol•ha −1 •year −1 in raceway ponds in Brazil, approaching the average sucrose and ethanol productivity from sugarcane.

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