[1] A newly discovered hydrothermal field on the ultraslow spreading Southwest Indian Ridge expands the known ranges of biogenic minerals, microbes, and hydrothermal deposits. The deposits from this vent site show typical characteristics of low-temperature hydrothermal deposits. Rare earth element fractionation might be partly influenced by bacterial activity. A physicochemical gradient is present across the layer of deposits, providing suitable microhabitats for various microbes. Molecular phylogenetic analysis demonstrates a diverse range of bacteria, some of which are involved in sulfur, iron, and nitrogen metabolism. A high diversity of biogenic Fe and Si minerals are present in the deposits. Biogenic silica, Fe-sulfides, and Fe-oxides with distinctive morphologies are closely related to microbes. Several novel Fe-oxide structures are found and attributed to new types of biogenic minerals. The precipitation of porous silica spherules and Fesulfides can be strongly promoted by extracellular polymer saccharides. Biomineralization features indicate that these deposits evolved through four stages. These results help us to better understand the formation of biogenic minerals and low-temperature deposits associated with microbes in the Earth's modern and ancient seafloor hydrothermal vent fields.Citation: Peng, X., S. Chen, H. Zhou, L. Zhang, Z. Wu, J. Li, J. Li, and H. Xu (2011), Diversity of biogenic minerals in lowtemperature Si-rich deposits from a newly discovered hydrothermal field on the ultraslow spreading Southwest Indian Ridge,

No abstract

Biofilms that grow around Gumingquan hot spring (T = 71 °C, pH = 9.2) in the Rehai geothermal area, Tengchong, China, are formed of various cyanobacteria, Firmicutes, Aquificae, Thermodesulfobacteria, Desulfurococcales, and Thermoproteales. Silicified virus-like nanoparticles, 40-200 nm in diameter, are common inside the microbial cells and the extracellular polymeric substances around the cells. These nanoparticles, which are formed of a core encased by a silica cortex, are morphologically akin to known viruses and directly comparable to silicified virus-like particles that were produced in biofilms cultured in the laboratory. The information obtained from examination of the natural and laboratory-produced samples suggests that viruses can be preserved by silicification, especially while they are still encased in their host cells. These results expand our views of virus-host mineral interaction in extreme thermal environments and imply that viruses can be potentially preserved and identified in the geological record.