Tisato Nicola, Torriani Stefano F F, Monteux Sylvain, Sauro Francesco, De Waele Jo, Tavagna Maria Luisa, D'Angeli Ilenia M, Chailloux Daniel, Renda Michel, Eglinton Timothy I, Bontognali Tomaso R R
University of Toronto, 35 St. George street, M5S 1A4 Toronto, (CA).
ETH Zurich, Institute of Integrative Biology, 8092 Zurich, (CH), now at: Syngenta Crop Protection, Münchwilen AG, Werk Stein, Schaffhauserstrasse, 4332 Stein AG, (CH).
Sci Rep. 2015 Oct 29;5:15525. doi: 10.1038/srep15525.
Helictites--an enigmatic type of mineral structure occurring in some caves--differ from classical speleothems as they develop with orientations that defy gravity. While theories for helictite formation have been forwarded, their genesis remains equivocal. Here, we show that a remarkable suite of helictites occurring in Asperge Cave (France) are formed by biologically-mediated processes, rather than abiotic processes as had hitherto been proposed. Morphological and petro-physical properties are inconsistent with mineral precipitation under purely physico-chemical control. Instead, microanalysis and molecular-biological investigation reveals the presence of a prokaryotic biofilm intimately associated with the mineral structures. We propose that microbially-influenced mineralization proceeds within a gliding biofilm which serves as a nucleation site for CaCO3, and where chemotaxis influences the trajectory of mineral growth, determining the macroscopic morphology of the speleothems. The influence of biofilms may explain the occurrence of similar speleothems in other caves worldwide, and sheds light on novel biomineralization processes.
螺旋石——一种出现在某些洞穴中的神秘矿物结构——与传统洞穴沉积物不同，因为它们的生长方向与重力相悖。虽然已经提出了关于螺旋石形成的理论，但其成因仍然不明确。在这里，我们表明，法国阿斯佩尔格洞穴中出现的一组引人注目的螺旋石是由生物介导的过程形成的，而不是如迄今为止所提出的非生物过程。形态学和岩石物理性质与纯物理化学控制下的矿物沉淀不一致。相反，微观分析和分子生物学研究揭示了与矿物结构密切相关的原核生物生物膜的存在。我们提出，微生物影响的矿化作用在滑动生物膜内进行，该生物膜作为碳酸钙的成核位点，并且在那里趋化作用影响矿物生长的轨迹，决定了洞穴沉积物的宏观形态。生物膜的影响可以解释全球其他洞穴中类似洞穴沉积物的出现，并为新的生物矿化过程提供线索。
