Nano-scale study of iron oxide/oxyhydroxide in hydrothermal vent microbial mat

Abstract

Hydrothermal vent systems consisting of hydrothermal vent, hydrothermal sediment and microbial mat are widely spread around the ocean, particularly spreading axis, continental margin and back-arc basin. Scientists have perceived that the hydrothermal systems, which reflect the primeval earth environment, are one of the best places to reveal the origin of life and extensive biogeochemical process of microbe-mineral interaction. Red-colored microbial mat recovered by Canadian scientific submersible ROPOS on South Pacific North Fiji basin KIOST hydrothermal vent expedition 1602 contains iron oxides and iron oxyhydroxides. Various morphologies of minerals in the red-colored microbial mat observed by Scanning Electron Microscopy (SEM) are mainly showed sheath shaped, resembled with Leptothrix microbial structure and stalks shaped, similar with Marioprofundus microbial structures. They are also detected with DNA analysis. The cross sectional observation of microbial structures encrusted with iron oxide and iron oxyhydroxide at a nano scale by Focused Ion Beam (FIB) technique, Transmission Electron Microscopy (TEM) and Scanning Transmission Electron Microscopy-spectrum image (STEM-SI) analysis was developed to verify the structural/biogeochemical properties in the microbe-mineral interaction. Systematic nano-scale measurements on the biomineralization in the microbial mat leads the understandings of biogeochemical environme