On the Beneficial Role of Silicon to Organisms: A Case Study on the Importance of Silicon Chemistry to Metal Accumulation in Yeast

Abstract

Silicon is involved in numerous important structural and functional roles in a wide range of organisms, including diatoms, plants, and humans, but clear mechanisms have been discovered only in diatoms and sponges. Silicate availability influences metal concentrations within various cell-and tissue-types, but a mechanism has not been discovered so far. In an earlier study on Baker's yeast Saccharomyces cerevisiae it was proposed that a chemical mechanism, rather than a biological one, is important. In the present study, the interaction of silicon with Baker's yeast is further investigated by studying the influence of zinc and magnesium on Si accumulation both at a low and a high silicate concentration in the medium. Si accumulation fitted well with Freundlich adsorption and Si release followed depolymerization kinetics, indicating that silicate adsorbs to the surface of the cell rather than being transported over the cell membrane. Subsequently, adsorbed silicate interacts with metal ions and, therefore, alters the cell's affinity for these ions. Since several metals are nutritional, these Si interactions can significantly change the growth and viability of organisms. In conclusion, the results show that chemistry is important in Si and metal accumulation in Baker's yeast, and suggest that similar mechanisms should be studied in detail in other organisms to unravel essential roles of Si.

Modern Views on Desilicification: Biosilica and Abiotic Silica Dissolution in Natural and Artificial Environments

“…Very little is known of biological silicate interactions in higher animals, and despite many efforts, a biological process or silicate binding site has not been identified so far. 29 The mechanism by which the silica particles become bound to the surface of the cells or partially dissolved by them is not clear. Silica is believed to play a critical role in bioactivity.…”

“…Current research ideas on silica toxicity and binding in the alveolar macrophage are reviewed and discussed by Hamilton et al 196 Probably silicate could play a role in organisms by its chemical interactions with metal ions. 28,29 Silicate-metal complexes could influence the availability of metals that are important for the organism (e.g., as an enzymatic cofactor). The effects on several biological processes could then be ascribed to the availability of important metal ions.…”

Laser-Induced Breakdown Spectroscopy and Phytolith Analysis: An Approach to Study the Deposition and Distribution Pattern of Silicon in Different Parts of Wheat (Triticum aestivum L.) Plant

“…Silicon reportedly increases crop quality and yield, protects the plants against fungal infection, insects, pest attack and increases disease resistance [5,17,26,27,38]. Silicon can also alleviate imbalance between zinc and phosphorus supply as well as decrease the toxic effect of aluminum in hydroponic culture in several species [3,9,44,56]. Similar applications of silicon have also been found in other cereals and dicotyledonous plants [11,25,41,48,53].…”

Compartmental Analysis Suggests Macropinocytosis at the Onset of Diatom Valve Formation

“…All chemicals used in this study were of analytical grade, obtained from Aldrich (Zwijndrecht, The Netherlands 4 solution (specific activity 4.8 TBq/g) was prepared as described earlier [32], and was successfully used earlier in Si uptake studies in yeast [13].…”

“…Diffusion of Si, however, has not been demonstrated in diatoms; it has been correlated to data obtained on rat liver mitochondria [12]. Recent studies on yeasts showed that diffusion of Si in particular occurs when the integrity of membranes is at stake [13]. As such a diffusion mechanisms for massive uptake of silicon in diatoms is questionable.…”