Previous molecular surveys indicated Acidimicrobium sp. were abundant in samples from hot (528C), acidic (pH 2), oligotrophic. Boiling Springs Lake (BSL) in ...
Geomicrobiology Journal (2015) 32, 140–157 Copyright © Taylor & Francis Group, LLC ISSN: 0149-0451 print / 1521-0529 online DOI: 10.1080/01490451.2014.935533
Isolation and Characterization of Novel Iron-Oxidizing Autotrophic and Mixotrophic Bacteria from Boiling Springs Lake, an Oligotrophic, Acidic Geothermal Habitat FRANCINE A. ARROYO1, PATRICIA L. SIERING1*, JENNIFER S. HAMPTON1, ANGELA MCCARTNEY1, MATTHEW P. HURST3, GORDON V. WOLFE2, and MARK S. WILSON1 1
Department of Biological Sciences. Humboldt State University, Arcata, California, USA Department of Biological Sciences, California State University, Chico, Chico, California, USA 3 Department of Chemistry, Humboldt State University, Arcata, California, USA 2
Received February 2014, Accepted June 2014
Previous molecular surveys indicated Acidimicrobium sp. were abundant in samples from hot (528C), 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: Acidimicrobium, iron oxidation, thermoacidophile
Introduction Boiling Springs Lake (BSL) is a 50–938C, pH 2.2, 18,000 m2, thermal feature located in Lassen Volcanic National Park (California, USA) (Siering et al. 2006; Siering et al. 2013; Wilson et al. 2008). The size, pH, chemistry, and temperature appear relatively stable based on summer measurements (1999–2013) despite some seasonal temperature depressions of up to 108C. BSL is a light-limited, oligotrophic (TOC and DOC »1 mg/L) system with total iron and sulfate concentrations of approximately 31 and 968 mg/L, respectively; all other metals are 80%
