Effect of sulphur on selenium accumulation and speciation in Nannochloropsis oceanica

Sulphur (S) and selenium (Se) are chemically similar. Once Se is taken up, it substitutes S in S-containing amino acids. This study investigated the effect of S on selenite accumulation in the microalga Nannochloropsis oceanica. [0-28 mM] S concentrations and selenite concentrations of 0 and 30 mu M were tested. S concentrations of <= 3 mM led to decreased cell growth whereas cultures with >= 4 mM were not growth limited. Se accumulation increased up to 8-fold when using S <= 2 mM and decreased with S 28 mM. The average relative abundance of organic Se species was selenomethionine (SeMet) 98.2 %, selenocystine (SeCys(2)) 1.4 % and selenomethyl selenocysteine (SeMeSeCys) 0.4 %. Total fatty acids were not affected by S limitation or Se presence. This is the first study on the effect of S on selenite accumulation, organic Se speciation of N. oceanica and its potential as an organic Se-enriched food/feed ingredient.

Automated summary

This study investigated the effect of sulphur on selenite accumulation in Nannochloropsis oceanica and found that lower sulphur concentrations increased selenium accumulation, while higher concentrations decreased it. The main organic selenium species identified was selenomethionine.