Selenium
Uptake and Methylation by the Microalga Chlamydomonas
reinhardtii
Bas Vriens
Renata Behra
Andreas Voegelin
Anze Zupanic
Lenny H. E. Winkel
10.1021/acs.est.5b04169.s001
https://acs.figshare.com/articles/journal_contribution/Selenium_Uptake_and_Methylation_by_the_Microalga_Chlamydomonas_reinhardtii/2086273
Biogenic selenium (Se) emissions
play a major role in the biogeochemical
cycle of this essential micronutrient. Microalgae may be responsible
for a large portion of these emissions via production of methylated
Se compounds that volatilize into the atmosphere. However, the biochemical
mechanisms underlying Se methylation in microalgae are poorly understood.
Here, we study Se methylation by Chlamydomonas reinhardtii, a model freshwater alga, as a function of uptake and intracellular
Se concentrations and present a biochemical model that quantitatively
describes Se uptake and methylation. Both selenite and selenate, two
major inorganic forms of Se, are readily internalized by C. reinhardtii, but selenite is accumulated around
ten times more efficiently than selenate due to different membrane
transporters. With either selenite or selenate as substrates, Se methylation
was highly efficient (up to 89% of intracellular Se) and directly
coupled to intracellular Se levels (<i>R</i><sup>2</sup> > 0.92) over an intracellular concentration range exceeding an
order
of magnitude. At intracellular concentrations exceeding 10 mM, intracellular
zerovalent Se was formed. The relationship between uptake, intracellular
accumulation, and methylation was used by the biochemical model to
successfully predict measured concentrations of methylated Se in natural
waters. Therefore, biological Se methylation by microalgae could significantly
contribute to environmental Se cycling.
2016-01-19 00:00:00
study Se methylation
intracellular Se concentrations
intracellular concentration range
Se methylation
intracellular Se levels
Microalga Chlamydomonas reinhardtiiBiogenic selenium
methylated Se compounds
intracellular zerovalent Se