The Effect of Titanium, Zirconium and Tin on the Growth of Diatom Synedra Acus and Morphology of Its Silica Valves

Author: Basharina Tatjana  

Publisher: Springer Publishing Company

ISSN: 1876-990X

Source: Silicon, Vol.4, Iss.4, 2012-10, pp. : 239-249

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

The effect of three Group IV metals (titanium, zirconium and tin) on the growth, morphology and chemical composition of the freshwater diatom Synedra acus subsp. radians (Kützing) Skabichevsky was studied and compared with germanium. The elements in their highest oxidation states were introduced into the culture medium in the form of hydroxides. Germanium was found to be toxic at ≥5 mol. % of the total Ge-Si content in the culture medium. In the presence of other elements, a slight decrease in the cell division rate was observed independent of the element within 1-15% content interval. The analysis of the obtained biomass and silica valves revealed the presence of all the added elements within the cells. However, only germanium was incorporated into the valves in considerable amounts. S. acus cultivation with the addition of 5% Group IV elements resulted in cells having the following aberrations in the structure of the silica valves: changes in valve shape, thickening of valves, alterations of the areolae rows, irregularity or absence of the areolae and a decrease in the mechanical strength of valves. Moreover, the effect of Group IV elements on silica formation was simulated in vitro using a synthetic polymer bearing polyamine and phosphate groups found in silaffines (proteins from diatom frustules). The studied elements were observed to provoke the formation of unstable silica particles in solution. We propose that the observed effects of germanium, titanium, zirconium and tin on diatom growth and structure are due to uncontrollable silica condensation.

Related content