De Windt Wim, Boon Nico, Siciliano Steven D, Verstraete Willy
Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Coupure Links 653, B-9000 Gent, Belgium.
Environ Microbiol. 2003 Nov;5(11):1192-202. doi: 10.1046/j.1462-2920.2003.00527.x.
In the absence of oxygen, a protective H2 film is formed around an Fe(0) surface, inhibiting the electron flow from this surface. Our study of anoxic corrosion of Fe(0) beads revealed that, in the presence of Shewanella oneidensis MR-1, H2 removal and precipitation of Fe mineral particles on the cell surface are determining processes for corrosion. These two biologically mediated processes were governed by cell density. H2 removal by Shewanella oneidensis was detected at cell concentrations of 1.0 x 10(6) live cells ml-1 and higher and H2 was electron donor for denitrification of NO3-. The removal of the protective H2 layer from Fe(0) beads by Shewanella oneidensis, resulted in an increase of Fe release out of the Fe(0) beads from 153 +/- 25 mg l(-1) to 196 +/- 7 mg l-1 after 20 h. When the cell concentration exceeded 1.0 x 10(8) live cells ml-1, precipitation of iron minerals on the cell surface was characteristic for the greatest percentage of MR-1 cells, whereas micrometre-scale iron precipitates not associated with culturable cell biomass significantly decreased in number. Addition of supernatant of a corrosion assay with high cell concentration induced metabolic activity in a corrosion assay with low cell concentration, resulting in increased H2 consumption and Fe release from Fe(0) beads. Homoserine lactone-like molecules were detected in the supernatant by a bio-assay, suggesting the involvement of a quorum-sensing regulatory mechanism.
在无氧条件下，Fe(0)表面会形成一层保护性的H₂膜，抑制电子从该表面流出。我们对Fe(0)珠粒的缺氧腐蚀研究表明，在存在希瓦氏菌MR-1的情况下，H₂的去除以及铁矿物颗粒在细胞表面的沉淀是腐蚀的决定性过程。这两个生物介导的过程受细胞密度的控制。在细胞浓度为1.0×10⁶个活细胞/毫升及以上时检测到希瓦氏菌对H₂的去除，H₂作为电子供体用于NO₃⁻的反硝化作用。希瓦氏菌从Fe(0)珠粒上去除保护性H₂层，导致20小时后Fe(0)珠粒中铁的释放量从153±25毫克/升增加到196±7毫克/升。当细胞浓度超过1.0×10⁸个活细胞/毫升时，铁矿物在细胞表面的沉淀是大多数MR-1细胞的特征，而与可培养细胞生物量无关的微米级铁沉淀物数量显著减少。添加高细胞浓度腐蚀试验的上清液会诱导低细胞浓度腐蚀试验中的代谢活性，导致H₂消耗增加以及Fe(0)珠粒中铁的释放。通过生物测定法在上清液中检测到了类高丝氨酸内酯分子，这表明存在群体感应调节机制。
