【摘要】 【目的】从深海热液区获取异化铁还原微生物(Dissimilatory iron reducing microorganisms,DIRM),分析其矿化速率和矿化产物,认识其参与的深海生物地球化学循环。【方法】以羟基氧化铁(FeOOH)为电子受体,以乙酸等简单有机物做电子供体,在60°C恒温厌氧条件下,对南大西洋中脊深海热液区硫化物样品中的DIRM进行富集、培养;采用扫描电镜(SEM)和透射电镜(TEM)、选区电子衍射(SAED)以及能谱仪(EDS)等方法对矿化产物进行形貌观察与成分分析。【结果】从2个硫化物样品中,共获得了139个铁还原培养物,它们均能将培养基中FeOOH (Fe3+90 mmol/L)转化为矿化产物。电镜下可见明显的晶体形态,以立方体形晶体为主,边长为5.0–20.0 nm;EDS分析表明,所有矿物晶体的主要元素为铁和氧,推测是由菱铁矿和磁铁矿组成的混合矿物。矿物晶体形成的时间差异较大,从3d到54d不等,多数培养物可在11 d到20 d内形成晶体。微生物多样性表明,培养物中优势菌主要为厚壁菌门(Firmicutes)和广古菌门(Euryarchaeota),包括一氧化碳胞菌(Carboxydocella)与脱硫肠状菌(Desulfotomaculum)近似新物种(16SrRNA基因同源性89%–91%)和广古菌地丸菌(Geoglobus)。【结论】热液区高温厌氧细菌与古菌可以利用简单有机物为电子供体进行铁还原,形成铁氧化物晶体。实验结果对于微生物参与铁元素的生物地球化学循环与矿物形成的潜力具有支持作用。然而它们是否参与了热液区铁元素的生物地球化学循环与矿物形成还需要大量研究工作验证。更多还原

【Abstract】 [Objective] To obtain the dissimilatory iron reducing microorganisms(DIRM) from deep sea hydrothermal fields, analyze their mineralization ability and mineralization products, to further understand their role in iron biogeochemical cycle. [Methods] We enriched and cultivated DIRM from polymetallic sulfides of South Mid-Atlantic Ridge hydrothermal fields with FeOOH as an electron acceptor, and acetic acid etc. as electron donor under the constant 60 °C temperature anaerobic condition. The morphology observation and elemental composition analysis on mineralized products were carried out by scanning electron microscope, transmission electron microscope, selected area electron diffraction and Energy Dispersive Spectrometer. [Results] We obtained a total of 139 iron reducing microbial cultures from 2 polymetallic sulfides. All of them could transform FeOOH(Fe3+ 90 mmol/L) into mineralized iron products with obvious crystal structure, mainly in cubic shape with side length ranged from 5.0 nm to 20.0 nm. According to Energy Dispersive Spectrometer analysis, the elements of all mineral crystals were iron and oxygen, presumably a mixed mineral composed crystal of siderite and magnetite. The time of formation of mineral crystals varies from 3 to 54 d, and most cultures can form crystals within 11 to 20 d. Microbial diversity indicated that the dominant microorganisms in the culture were mainly Firmicutes and Euryarchaeota, including Carboxydocella and Desulfotomaculum, a new species(16 S rRNA Homology 89%–91%) and Geoglobus. [Conclusion] At 60 °C, bacteria and archaea in hydrothermal fields could transform ferric iron to mixed iron oxides mineral with the simple organic compounds as electron donor. These results supported the potential of microorganisms to participate in the biogeochemical cycle and mineralization. However, it requires extensive research work to verify their roles in situ.更多还原