Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Innovation Academy for Earth Sciences, Chinese Academy of Sciences, Beijing 100029, China.
Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China.
Sci Adv. 2022 May 13;8(19):eabn6045. doi: 10.1126/sciadv.abn6045.
Biosilicification-the formation of biological structures composed of silica-has a wide distribution among eukaryotes; it plays a major role in global biogeochemical cycles, and has driven the decline of dissolved silicon in the oceans through geological time. While it has long been thought that eukaryotes are the only organisms appreciably affecting the biogeochemical cycling of Si, the recent discoveries of silica transporter genes and marked silicon accumulation in bacteria suggest that prokaryotes may play an underappreciated role in the Si cycle, particularly in ancient times. Here, we report a previously unidentified magnetotactic bacterium that forms intracellular, amorphous silica globules. This bacterium, phylogenetically affiliated with the phylum Nitrospirota, belongs to a deep-branching group of magnetotactic bacteria that also forms intracellular magnetite magnetosomes and sulfur inclusions. This contribution reveals intracellularly controlled silicification within prokaryotes and suggests a previously unrecognized influence on the biogeochemical Si cycle that was operational during early Earth history.
生物硅化作用——由二氧化硅组成的生物结构的形成——在真核生物中广泛存在；它在全球生物地球化学循环中起着重要作用，并通过地质时间导致海洋中溶解硅的减少。虽然长期以来人们一直认为真核生物是唯一对硅的生物地球化学循环有显著影响的生物，但最近发现的硅转运蛋白基因和细菌中明显的硅积累表明，原核生物可能在硅循环中扮演着被低估的角色，尤其是在古代。在这里，我们报告了一种以前未被识别的磁细菌，它形成细胞内无定形的二氧化硅小球。这种细菌与硝化螺旋菌门有亲缘关系，属于一个分支很深的磁细菌群，该群细菌还形成细胞内的磁铁矿磁小体和硫包体。这一发现揭示了原核生物中细胞内控制的硅化作用，并表明对早期地球历史上运行的生物地球化学硅循环有以前未被认识到的影响。
