Effect of phosphorus limitation on Se uptake efficiency in the microalga Nannochloropsis oceanica.

[Display omitted] • P limitation increased Se uptake efficiency in Nannochloropsis oceanica. • Higher Se uptake efficiency led to higher Se toxicity. • Se accumulation was positively correlated with cell growth. • P 200 and Se 5 were considered the optimal concentrations for Se-enrichment. Microalgae are considered an efficient accumulator and promising source of Se for feed additive purposes. This study aimed at investigating, for the first time, the effect of phosphorus limitation on Se accumulation and uptake efficiency in N. oceanica. A range of phosphorus concentrations (0–2470 µM) were tested in either the presence or absence of sodium selenite (0, 5, 30 µM). Se accumulation was increased up to 16-fold and Se uptake efficiency was increased up to 3.6-fold under phosphorus growth-limiting concentrations. N. oceanica was then cultivated in a 1.8 L flat-panel photobioreactor in batch operation under two phosphorus growth-limiting concentrations (250 and 750 µM) where the accumulation of Se in the microalgal biomass, as well as its presence in the spent medium were analysed. This study is the first to investigate the effect of phosphorus limitation for increasing Se accumulation in microalgae, and to prevent the release of Se in wastewater. [ABSTRACT FROM AUTHOR]