Distribution of selenium and iodine in Chlorella cells enriched during cultivation
| Authors | |
|---|---|
| Year of publication | 2005 |
| Type | Article in Proceedings |
| Conference | 6th European Workshop of European society of Microalgal Biotechnology |
| MU Faculty or unit | |
| Citation | |
| Field | Analytic chemistry |
| Keywords | selenium; iodine; algae; Chlorella |
| Description | Selenium (Se) and iodine (I) as essential microelements have a great importance in human and animal health. Se deficiency in pathogenesis of diseases as cancer, cardiovascular, autoimmune or mental have been proved. Iodine deficiency leads to serious disorders associated with growth and development. Both Se and I play substantial role in thyroid hormone regulation. The availability of the above elements depends on their chemical form. It was found, that utilization of organic Se or I by the organism is higher than inorganic source of them. This work is focused on determination of iodine or selenium forms in chlorella cells grown in inorganic media enriched by selenite or iodide salts. The mixotrophic strain of Chlorella sp. was grown in fed-batch mode either in open solar bioreactor, with CO2 as a carbon source, or heterotrophically in fermentor with glucose as a source of carbon. Fractionation protocol including sequential extraction by chloroform, water and sodium dodecylsulphate solution was designed. Inductively coupled plasma optical emission or mass spectrometry was employed for determination of element content in fractions. Fractions were solubilized with tetramethylammonium hydroxide for determination of iodine or digested with nitric acid at 160şC for determination of selenium. Inorganic non-metabolized anions (iodide, selenite) were quantified in aqueous extract using vapour-generation ICP-OES after separation on anion exchange resin. Fractionation gives information on the content of element in non-polar, protein, polar water-soluble and non-soluble organic fractions and inorganic anions. Methodology was applied in analysis of algae samples that were cultivated under both photoautotrophic and hetrotrophic conditions. Metabolization of iodine to organic forms is likely better for autotrophic cultivation, where higher content of organic-bound iodine can be found in algae biomass. In case of selenized Chlorella, autotrophic cultivation results in higher total selenium content as well as higher percentage of protein-bound element compared to heterotrophic conditions. |
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