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

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 Electronic supplementary material The online version of this article (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.

Biogenic nanomaterials from photosynthetic microorganisms

“…The germanium, titanium, zirconium and tin were all found to be taken up by the silicon deposition vesicle (SDV) whereas the germanium disturbed the biosilicification process, causing frustule aberrations. However, the Ti, Zr and Sn were found to inhibit the biosilicification process in this species [47]. With respect to Ge, the conclusions of Basharina et al are consistent with previous studies which also report the incorporation of Ge into the frustules and the resulting changes in morphology [42,43,48,49].…”

“…Basharina et al [47] studied the effect of the incorporation of group IV metals (titanium, germanium, zirconium and tin) into diatom biosilica and found that these metals are taken up concomitantly into the cells with Si(OH) 4 , in their hydroxyl form, but only germanium was incorporated in significant quantities within the biosilica. The germanium, titanium, zirconium and tin were all found to be taken up by the silicon deposition vesicle (SDV) whereas the germanium disturbed the biosilicification process, causing frustule aberrations.…”

Effect of Metals, Metalloids and Metallic Nanoparticles on Microalgae Growth and Industrial Product Biosynthesis: A Review

“…Lithium (Li) can alter the length and form of flagella in Chlamydomonas reinhardtii [ 28 ] or affect the structure of polysaccharide sheath around Ankistrodesmus gracilis cells [ 29 ], and can also at various concentrations inhibit other microalgae strains [ 30 , 31 ]. Cultivation of diatom Synedra acus in the presence of germanium (Ge), titanium (Ti), zirconium (Zr) or tin (Sn) caused alterations in shape, size and mechanical strength of silica valves in Synedra frustules [ 32 ].…”

Titanium uptake and incorporation into silica nanostructures by the diatom Pinnularia sp. (Bacillariophyceae)

“…TiO 2 (Jeffryes et al 2008 ; Lang et al 2013 ) and GeO 2 (Gale et al 2011 ) have been incorporated by bio-uptake or deposited on the frustules post-cleaning. GeO 2 has been shown to inhibit diatom growth (Shea and Chopin 2007 ) and to interfere with frustule synthesis (Basharina et al 2012 ). The uptake of other elements may be regulated as a function of concentrations, and there will be biological limits to the amount of a specific element that can be incorporated.…”