硅藻细胞壁硅化过程中有机质-矿物的相互作用

Organic Matrix-Mineral Interaction during Cell Wall Silicification in Diatoms

生物成因二氧化硅,更为确切地说是无定形水合二氧化硅,是第二大类生物成因矿物,在丰度和分布上仅次于生物成因碳酸盐矿物。硅藻是海洋生物成因二氧化硅的主要贡献者,其复杂和多级结构的硅质细胞壁已经引起多学科研究的兴趣。生物化学研究表明,硅藻生物成因的二氧化硅是一种复合材料,除了无机的非晶质二氧化硅以外,还含有生物矿化过程中普遍存在的有机组分,例如多糖、蛋白质和长链聚胺等。对这些组分的功能研究显示,它们在诱导二氧化硅沉淀以及形成物种特异性纳米图案方面起着至关重要的作用。本文简要介绍硅藻和硅藻细胞壁组成和结构,同时着重介绍了硅化过程中的有机和生物分子的生物功能、提取于生物二氧化硅中矿化相关的有机分子参与的体外(invitro)实验以及模型有机添加剂存在下的仿生矿化等研究的最新进展。对硅藻调控的生物成因二氧化硅形成机制的深入了解,将可能从机理上把全球硅循环和碳循环联系起来;而对硅藻体内成分的鉴定和分类将有助于我们深入理解石油的物质来源和硅藻的进化历程。

Biosilica, more specifically hydrated amorphous silica, often referred to as opal, is the second most abundant mineral type formed by organisms, with only the carbonate minerals exceeding it in abundance and distribution. As the predominant contributor to biosilica in the oceans, diatoms are known for the intricate geometries and spectacular patterns of their silica- based cell walls. Biochemical studies demonstrate that diatom biosilica is a composite material containing several general organic components in addition to inorganic silica, such as polysaccharides, long-chain polyamines and zwitterionic proteins. Functional studies on these organic components indicate that they play a crucial role in guiding silica precipitation as well as in the formation of species-specific nanopatterns. This article gives an overview of current knowledge on the function of above-mentioned organic and biological molecules in biosilicification. Moreover, some studies of biomimetic mineralization using model organic additives and in vitro experiments using molecules extracted from organisms are also involved. An insight into the silicification mechanisms in diatoms will link the global cycles for Si and C mechanistically, whereas identification and classification of the components in diatoms may assist us in deeper understanding of material sources of petroleum and the evolutionary development of diatoms.