Open AccessIsolation and Distribution of a Novel Iron-Oxidizing Crenarchaeon from Acidic Geothermal Springs in Yellowstone National Park
Author(s) -
Mark A. Kozubal,
Richard E. Macur,
S. Korf,
W. P. Taylor,
G. Ackerman,
Ákos Nagy,
William P. Inskeep
Publication year - 2008
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.01200-07
Subject(s) - thermophile , hot spring , 16s ribosomal rna , archaea , oxidizing agent , strain (injury) , extremophile , biology , chemistry , microbiology and biotechnology , environmental chemistry , bacteria , biochemistry , gene , genetics , paleontology , organic chemistry , anatomy
Novel thermophilic crenarchaea have been observed in Fe(III) oxide microbial mats of Yellowstone National Park (YNP); however, no definitive work has identified specific microorganisms responsible for the oxidation of Fe(II). The objectives of the current study were to isolate and characterize an Fe(II)-oxidizing member of theSulfolobales observed in previous 16S rRNA gene surveys and to determine the abundance and distribution of close relatives of this organism in acidic geothermal springs containing high concentrations of dissolved Fe(II). Here we report the isolation and characterization of the novel, Fe(II)-oxidizing, thermophilic, acidophilic organismMetallosphaera sp. strain MK1 obtained from a well-characterized acid-sulfate-chloride geothermal spring in Norris Geyser Basin, YNP. Full-length 16S rRNA gene sequence analysis revealed that strain MK1 exhibits only 94.9 to 96.1% sequence similarity to other knownMetallosphaera spp. and less than 89.1% similarity to knownSulfolobus spp. Strain MK1 is a facultative chemolithoautotroph with an optimum pH range of 2.0 to 3.0 and an optimum temperature range of 65 to 75°C. Strain MK1 grows optimally on pyrite or Fe(II) sorbed onto ferrihydrite, exhibiting doubling times between 10 and 11 h under aerobic conditions (65°C). The distribution and relative abundance of MK1-like 16S rRNA gene sequences in 14 acidic geothermal springs containing Fe(III) oxide microbial mats were evaluated. Highly related MK1-like 16S rRNA gene sequences (>99% sequence similarity) were consistently observed in Fe(III) oxide mats at temperatures ranging from 55 to 80°C. Quantitative PCR usingMetallosphaera -specific primers confirmed that organisms highly similar to strain MK1 comprised up to 40% of the total archaeal community at selected sites. The broad distribution of highly related MK1-like 16S rRNA gene sequences in acidic Fe(III) oxide microbial mats is consistent with the observed characteristics and growth optima ofMetallosphaera -like strain MK1 and emphasizes the importance of this newly described taxon in Fe(II) chemolithotrophy in acidic high-temperature environments of YNP.