Arsenic uptake in bacterial calcite

Abstract

Bio-mediated processes for arsenic (As) uptake in calcite were investigated by means of X-ray Diffraction (XRD) and Xray Absorption Spectroscopy (XAS) coupled with X-ray Fluorescence measurements. The environmental bacterial strain Bacillus licheniformis BD5, sampled at the Bullicame Hot Springs (Viterbo, Central Italy), was used to synthesize calcite from As-enriched growth media. Both liquid and solid cultures were applied to simulate planktonic and biofilm community environments, respectively. Bacterial calcite samples cultured in liquid media had an As enrichment factor (Kd) 50 times higher than that from solid media. The XRD analysis revealed an elongation of the crystal lattice along the c axis (by 0.03 Å ) for biogenic calcite, which likely resulted from the substitution of larger arsenate for carbonate in the crystal. The XAS data also showed a clear difference in the oxidation state of sorbed As between bacterial and abiotic calcite. Abiotic chemical processes yielded predominantly As(V) uptake whereas bacterial precipitation processes led to the uptake of both As(III) and As(V). The presence of As(III) in bacterial calcite is proposed to result from subsequent reduction of arsenate to arsenite by bacterial activities. To the best of our knowledge, this is the first experimental observation of the incorporation of As(III) in the calcite crystal lattice, revealing a critical role of biochemical processes for the As cycling in nature.

Simultaneous Adsorption and Incorporation of Sr2+ at the Barite (001)–Water Interface

“…On the muscovite (001) surface, cation adsorption occurs by electrostatic attraction to the negatively charged surface. On the calcite (104) surface, which is nominally neutral at circumneutral pH, ion sorption occurs though a range of mechanisms, including simple adsorption, − , incorporation (e.g., Pb substituting for Ca or arsenate incorporated in the crystal defects), and precipitation (e.g., formation of epitaxial films). On barite, incorporation is limited to the topmost portion of the barite surface.…”

Bioaccessible arsenic in soil of thermal areas of Viterbo, Central Italy: implications for human health risk

“…In natural travertines, As(III) can be incorporated in calcite through the substitution of AsO 3 3for CO 3 2- (Bardelli et al, 2011;Di Benedetto et al, 2006). Recently, As(V) has been documented in the crystal lattice of calcite precipitating at Bullicame, while both As(V) and As(III) species were observed in biogenic calcites produced by the As-resistant bacterium B. Licheniformis, synthesized under laboratory condition on a solid medium (Catelani et al, 2018). Data show that As-rich calcite dissolution from travertine likely controls As translocation in natural soils of the Viterbo area.…”

“…Similar results were obtained by Dessau ( 1968 ), who documented up to 220 mg/kg of As in the travertine of Viterbo thermal springs (the exact location of the sampled spring is not given), and by Di Benedetto et al ( 2011 ) in the travertine of Piscine Carletti spring (85–213 mg/kg As). Arsenic is often widespread in hot spring deposits (e.g., Webster and Nordstrom, 2003 ), but not many works investigated As in the associated travertine (Pentecost, 2005 ; Catelani et al, 2018 ). In addition to Costagliola et al ( 2013 ), travertines with concentrations of As of hundreds to thousands mg/kg were documented in Iran (Hamidian et al, 2019 ; Khorasanipour & Esmaeilzadeh, 2015 ), Greece (Kampouroglou et al, 2017 ; Winkel et al, 2013 ), and Turkey (Dogan & Dogan, 2007 ), commonly associated with tectonically active areas, where the waning stages of Quaternary volcanic activity set up hydrothermal circulation at a basin scale, vehiculating emissions of CO 2 -rich fluids to the surface (Minissale et al, 2002 ).…”

Geochemical evidence for arsenic cycling in living microbialites of a High Altitude Andean Lake (Laguna Diamante, Argentina)

“…The presence of As(III) in the calcite structure has been related with the occurrence of biological process, for example, a significant fraction of As(III) has been detected in natural calcite from travertine deposits of Central Italy (Di Benedetto et al, 2006;Bardelli et al, 2011). More recently, the incorporation of As(III) was detected in biogenic calcite precipitated from bacteria cultures but not in the abiotic control incubations (Catelani et al, 2018). Hence, the presence of As(III) in the globules ({As1} in fig.…”