The dynamics of cyanobacterial silicification: An infrared micro-spectroscopic investigation
The dynamics of cyanobacterial silicification: An infrared micro-spectroscopic investigation
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DOI：
10.1016/s0016-7037(03)00488-5
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发表时间：
2004-02-01
影响因子：
5
通讯作者：
Konhauser, KO
中科院分区：
文献类型：
--
作者：
Benning, LG;Phoenix, VR;Konhauser, KO
采用同步加速器傅立叶变换红外微光谱技术研究了蓝藻硅化的动力学过程。在一系列微生物吸附二氧化硅或二氧化硅铁负荷依次增加的微环境中，测定了钙思菌单丝的外聚多糖和二氧化硅振动特性随时间的变化。利用特定红外光谱特征的强度和积分面积的变化建立了经验定量动态模型，并推导出生物矿化过程中每个准平衡阶段的二氧化硅负载相关参数。光谱特征的变化程度源于硅/多糖组合区域（Si-O/C-O, 1150-950 cm(-1)）和硅- o波段（800 cm(-1)）的集成面积的增加，后者代表了水合无定形SiO4四面体对应的特定硅键。从变化的程度出发，推导了一个过程同步变化的两阶段模型。在第一阶段，观察到细胞周围的外聚多糖鞘厚度的生物控制增加。在第二阶段，蓝藻细胞表面二氧化硅的无机控制积累是由混合Si-O/C-O光谱区积分面积的变化引起的。在800 cm（-1）处奇异Si-O波段的生长表明，非微生物伴生无机SiO4单元的同步形成进一步证实了第二个过程。在硅化过程中，二氧化硅的积累(1)独立于鞘多糖的生长，(2)通过从硅氧烷键中排出水来增加二氧化硅聚合物的链长。红外光谱证据表明，一个无机的、表面催化的过程，导致二氧化硅纳米球在蓝藻表面的积累，控制了第二阶段。在有铁存在的实验中，硅化遵循类似的途径，但在低硅负载下，铁与细胞表面的结合略微增强了反应动力学。版权所有2004爱思唯尔有限公司
The dynamics of cyanobacterial silicification was investigated using synchrotron-based Fourier transform infrared micro-spectroscopy. The changes in exo-polymeric polysaccharide and silica vibrational characteristics of individual Calothrix sp. filaments was determined over time in a series of microcosms in which the microbially sorbed silica or silica and iron load was increased sequentially. The changes in intensity and integrated area of specific infrared spectral features were used to develop an empirical quantitative dynamic model and to derive silica load-dependent parameters for each quasi-equilibrium stage in the biomineralization process.The degree of change in spectral features was derived from the increase in integrated area of the combined silica/polysaccharide region (Si-O/C-O, at 1150-950 cm(-1)) and the Si-O band at 800 cm(-1), the latter representing specific silica bonds corresponding to hydrated amorphous SiO4 tetrahedra. From the degree of change, a two-phase model with concurrent change in process was derived. In the first phase, a biologically controlled increase in thickness of the exo-polymeric polysaccharide sheath around the cell was observed. In phase two, a transition to an inorganically controlled accumulation of silica on the surface of the cyanobacterial cells was derived from the change in integrated area for the mixed Si-O/C-O spectral region. This second process is further corroborated by the synchronous formation of non-microbially associated inorganic SiO4 units indicated by the growth of the singular Si-O band at 800 cm(-1). During silicification, silica accumulates (1) independently of the growth of the sheath polysaccharides and (2) via an increase in chain lengths of the silica polymers by expelling water from the siloxane bonds. IR evidence suggest that an inorganic, apparently surface catalyzed process, which leads to the accumulation of silica nanospheres on the cyanobacterial surfaces governs this second stage. In experiments where iron was present, the silicification followed similar pathways, but at low silica loads, the iron bound to the cell surfaces slightly enhanced the reaction dynamics. Copyright (C) 2004 Elsevier Ltd