Abiotic Deposition of Fe Complexes onto Leptothrix Sheaths

Biology

Eisuke Taketa¹  Tatsuki Kunoh¹  Hideki Hashimoto¹  Tomoko Suzuki¹  Jun Takada¹  Mikio Takano¹  Naoaki Hayashi¹  Hitoshi Kunoh¹  Katsunori Tamura¹  Ian R. McFarlane²  Mohamed Y. El-Naggar² 

[1] Core Research for Evolutionary Science and Technology (CREST), Japan Science and Technology Agency (JST), Okayama 700-0082, Japan;Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089, USA;

关键词: Leptothrix cholodnii SP-6;    abiotic oxidation;    Fe(III) particles;    sheath;    direct deposition;   

DOI  :  10.3390/biology5020026

来源: DOAJ

【 摘 要 】

Bacteria classified in species of the genus Leptothrix produce extracellular, microtubular, Fe-encrusted sheaths. The encrustation has been previously linked to bacterial Fe oxidases, which oxidize Fe(II) to Fe(III) and/or active groups of bacterial exopolymers within sheaths to attract and bind aqueous-phase inorganics. When L. cholodnii SP-6 cells were cultured in media amended with high Fe(II) concentrations, Fe(III) precipitates visibly formed immediately after addition of Fe(II) to the medium, suggesting prompt abiotic oxidation of Fe(II) to Fe(III). Intriguingly, these precipitates were deposited onto the sheath surface of bacterial cells as the population was actively growing. When Fe(III) was added to the medium, similar precipitates formed in the medium first and were abiotically deposited onto the sheath surfaces. The precipitates in the Fe(II) medium were composed of assemblies of globular, amorphous particles (ca. 50 nm diameter), while those in the Fe(III) medium were composed of large, aggregated particles (≥3 µm diameter) with a similar amorphous structure. These precipitates also adhered to cell-free sheaths. We thus concluded that direct abiotic deposition of Fe complexes onto the sheath surface occurs independently of cellular activity in liquid media containing Fe salts, although it remains unclear how this deposition is associated with the previously proposed mechanisms (oxidation enzyme- and/or active group of organic components-involved) of Fe encrustation of the Leptothrix sheaths.

【 授权许可】

Unknown