Isolation and Characterization of Novel Iron-Oxidizing Autotrophic and Mixotrophic Bacteria from Boiling Springs Lake, an Oligotrophic, Acidic Geothermal Habitat

Abstract

AbstractPrevious molecular surveys indicated Acidimicrobium sp. were abundant in samples from hot (52˚C), acidic (pH 2), oligotrophic Boiling Springs Lake (BSL) in Lassen Volcanic National Park. We isolated and characterized Acidimicrobium sp. and functionally related bacteria from BSL. The pH and temperature optima of all isolates correlate with the average summer conditions of BSL suggesting these organisms are capable of active growth in BSL. Acidimicrobium isolates were capable of oxidizing iron when grown mixotrophically or autotrophically. The isolates also oxidized iron after growth cessation, suggesting a possible role of iron oxidation in maintaining homeostasis in the absence of population growth.Keywords: Acidimicrobiumiron oxidationthermoacidophile AcknowledgmentsThe authors thank D. Barrie Johnson for advice on culturing and maintenance of the type strain, and Casey Lu for assistance and use of equipment for electron microscopy. We also acknowledge the NPS LVNP staff, especially Louise Johnson and Michael Magnuson, for their generous efforts assisting with site access. FundingFunding was provided by the National Science Foundation (#MCB-0702018 and #MCB-0702069), and HSU Howard Hughes Medical Institute undergraduate science education grant (#52002680). The authors of this manuscript have no conflicts of interest to declare with respect to publication of this manuscript.