Biomineralization processes in modern calcareous tufa: Possible roles of viruses, vesicles and extracellular polymeric substances (Corvino Valley – Southern Italy)

Abstract

A modern lithifying biofilm, associated with fluvial calcareous tufa in southern Italy, is composed of a complex community of micro‐organisms including autotrophic and heterotrophic bacteria, together with likely viruses (bacteriophages) and bacterial vesicles. Produced by most of the bacterial forms, extracellular polymeric substances are widespread and are the main sites of mineral precipitation, rather than the microbial cells themselves, but viruses and vesicles also appear to be mineralized. Neoformed biominerals replace these organic substrates starting with an amorphous phase rich in Ca, Si and several other cations followed by two different types of proto‐crystal: a granular−irregular Ca‐rich type and a lamellar/fibrous Si‐Al‐Mg‐rich type. Their growth leads to the formation of Ca‐carbonate and Mg‐silicate crystals that preserve their initial different habits. The coeval precipitation of silicate and carbonate at the initial stage of bio‐mediated mineral formation is a process common within freshwater and saline to hypersaline‐water calcareous microbialites. This is most probably related to the initial formation of poorly‐crystallized Mg‐Si phases that precipitate within the extracellular polymeric substances, related to the rise of pH in the zone of active oxygenic photosynthesis, and the mineralization of viruses, associated with the successive nucleation of Ca‐carbonate in close proximity to bacterial degradation of organic matter.

Effect of Alcaligenes sp. on corrosion behavior of X65 steel in simulated offshore oilfield-produced water

“…On the other hand, the presence of Alcaligenes sp. promotes the generation of stable corrosion products Fe 2 O 3 and Fe 3 O 4 , and EPS is an ideal nucleation site for mineral deposition, which can be used as a binding site for Ca 2+ and Mg 2+ , leading to the deposition of calcite structured CaCO 3 and Mg (OH) 2 minerals (Spadafora et al, 2010;Perri et al, 2022). Therefore, the impedance film value of the Alcaligenes sp.…”

Microbial influence on dolomite and authigenic clay mineralisation in dolocrete profiles of NW Australia

“…A variety of authigenic Mg‐clays, including t‐smectite (stevensite and kerolite) and palygorskite‐sepiolite, have been observed to have formed in association with carbonate and EPS in saline and alkaline lacustrine and marine environments (e.g. Calvo et al, 1999; Eardley, 1938; Leguey et al, 2010; Léveillé et al, 2002; Perri et al, 2022). Microbially influenced mineralisation of other silicates, such as Al and Fe silicates, has also been demonstrated in different environments (e.g.…”

“…The presence of hollow spheres composed of dolomite nanocrystals may Folk, 1993;Van Lith et al, 2003;Vasconcelos & McKenzie, 1997), experimental observations by Bontognali et al (2008) found that EPS excreted from the cell wall was the main site of nucleation and mineralisation. Some 100 nm-sized nanospheroids could be permineralised bacterial vesicles and viruses, as described from modern tufa by Perri et al (2022).…”

Do bacterial viruses affect framboid-like mineral formation?

“…In laboratory experiments, bacteriophages were also shown to likely influence vaterite formation -a metastable form of calcium carbonate (Słowakiewicz et al, 2021). A few studies have been conducted so far in relation to modern siliceous (Daughney et al, 2004;Laidler and Stedman, 2010;Peng et al, 2013), iron-rich (Kyle et al, 2008;Orange et al, 2011), carbonate (Pacton et al, 2015;Słowakiewicz et al, 2021;Perri et al, 2022), and microbial mat (De Wit et al, 2015;Perri et al, 2018;Pennafirme et al, 2019;Pacton et al, 2014;Carreira et al, 2015) environments. Therefore, in light of the abovementioned works, bacteriophages might play a role in various sedimentation processes.…”