RT Journal Article
T1 Troubles With Tubules: How Do Iron-Mineral Chemical Gardens Differ From Iron-Mineralized Sheaths of Iron Oxidizing Bacteria?
A1 Melanie Podbielski, 
A1 Knoll, Pamela
A1 Brown, Georgia
A1 Huld, Sigrid
A1 Neubeck, Anna
A1 Cartwright, Julyan H. E.
A1 Sainz Díaz, Ignacio
A1 Pimentel Guerra, Carlos
A1 McMahon, Sean
AB Microscopic tubules and filaments composed of iron minerals occur in various rock types of all ages. Although typically lacking carbonaceous matter, many are reasonably interpreted as the remains of filamentous microorganisms coated with crystalline iron oxyhydroxides. Iron-oxidizing bacteria (IOB) acquire such a coating naturally during life. However, recent debates about purported microfossils have highlighted the potential for self-organized nonbiological mineral growth (particularly in chemical gardens) to form compositionally and morphologically similar tubules. How can biogenic and abiogenic iron-mineral tubules be differentiated? Here, we use optical and electron microscopy and Mössbauer spectroscopy to compare the composition, microtexture, and morphology of ferruginous chemical gardens and iron-mineralized sheaths of bacteria in the genus Leptothrix. Despite broad morphological similarity, we find that Leptothrix exhibits a narrower range of filament diameters and lower filament tortuosity than chemical gardens. Chemical gardens produced from a ferrous salt also tend to incorporate Fe2+ whereas Leptothrix sheaths predominantly do not. Finally, the oxyhydroxides formed in Leptothrix sheaths tend to be smoother and denser on the inward-facing side, rougher and sparser on the outward side, whereas for chemical garden tubules the reverse is true. Some of these differences show promise for the diagnosis of natural samples.
PB Wiley
SN 1472-4677
YR 2025
FD 2025-05-14
LK https://hdl.handle.net/20.500.14352/120521
UL https://hdl.handle.net/20.500.14352/120521
LA eng
NO Podbielski, M., Knoll, P., Brown, G., Huld, S., Neubeck, A., Cartwright, J. H. E., Sainz‐Díaz, C. I., Pimentel, C., & McMahon, S. (2025). Troubles with tubules: How do iron‐mineral chemical gardens differ from iron‐mineralized sheaths of iron oxidizing bacteria? Geobiology, 23(3), e70021. https://doi.org/10.1111/gbi.70021
NO UKRI Biotechnology and Biological Sciences Research Council
NO RSE Saltire International Collaboration Award
NO Human Frontiers Science Program
DS Docta Complutense
RD 16 dic 2025