Isolation of a Leptothrix Strain, OUMS1, from Ocherous Deposits in Groundwater
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Leptothrix species in aquatic environments produce uniquely shaped hollow microtubules composed of aquatic inorganic and bacterium-derived organic hybrids. Our group termed this biologically derived iron oxide as “biogenous iron oxide (BIOX)”. The artificial synthesis of most industrial iron oxides requires massive energy and is costly while BIOX from natural environments is energy and cost effective. The BIOX microtubules could potentially be used as novel industrial functional resources for catalysts, adsorbents and pigments, among others if effective and efficient applications are developed. For these purposes, a reproducible system to regulate bacteria and their BIOX productivity must be established to supply a sufficient amount of BIOX upon industrial demand. However, the bacterial species and the mechanism of BIOX microtubule formation are currently poorly understood. In this study, a novel Leptothrix sp. strain designated OUMS1 was successfully isolated from ocherous deposits in groundwater by testing various culture media and conditions. Morphological and physiological characters and elemental composition were compared with those of the known strain L. cholodnii SP-6 and the differences between these two strains were shown. The successful isolation of OUMS1 led us to establish a basic system to accumulate biological knowledge of Leptothrix and to promote the understanding of the mechanism of microtubule formation. Additional geochemical studies of the OUMS1-related microstructures are expected provide an attractive approach to study the broad industrial application of bacteria-derived iron oxides.
Biogenous iron oxide
Energy-dispersive X-ray spectroscopy
Inductively coupled plasma mass spectrometry
Mineral solution vitamin
Mineral solution vitamin pyruvate
Scanning electron microscopy
Silicon iron glucose peptone
This research was supported by grant-in-aid for a special research project (2008–2013) from the Ministry of Education, Science, Culture, and Sports of Japan. We are indebted to Professor Ralph Mitchell of the School of Applied Science and Environment, Harvard University, USA, for his critical reviewing and valuable suggestions. We are also grateful for the invaluable advice and suggestions of Professors M. Seno, T. Shiraishi, T. Toyoda, T. Fujii, M. Nakanishi, and T. Kanao of the School of Natural Sciences and Technology, Okayama University.
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