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Applied and Environmental Microbiology, August 2008, p. 4877-4888, Vol. 74, No. 15
0099-2240/08/$08.00+0 doi:10.1128/AEM.00455-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.
Spatial and Temporal Patterns in the Microbial Diversity of a Meromictic Soda Lake in Washington State
,
Pedro A. Dimitriu,1*
Holly C. Pinkart,2
Brent M. Peyton,3 and
Melanie R. Mormile1
Biological Sciences Department, University of Missouri—Rolla, Rolla, Missouri 65409-1120,1 Department of Biological Sciences, Central Washington University, Ellensburg, Washington 98926,2 Chemical and Biological Engineering, Montana State University, Bozeman, Montana 59717-39203
Received 25 February 2008/ Accepted 4 June 2008
The microbial community diversity and composition of meromictic Soap Lake were studied using culture-dependent and culture-independent approaches. The water column and sediments were sampled monthly for a year. Denaturing gradient gel electrophoresis of bacterial and archaeal 16S rRNA genes showed an increase in diversity with depth for both groups. Late-summer samples harbored the highest prokaryotic diversity, and the bacteria exhibited less seasonal variability than the archaea. Most-probable-number assays targeting anaerobic microbial guilds were performed to compare summer and fall samples. In both seasons, the anoxic samples appeared to be dominated by lactate-oxidizing sulfate-reducing prokaryotes. High numbers of lactate- and acetate-oxidizing iron-reducing bacteria, as well as fermentative microorganisms, were also found, whereas the numbers of methanogens were low or methanogens were undetectable. The bacterial community composition of summer and fall samples was also assessed by constructing 16S rRNA gene clone libraries. A total of 508 sequences represented an estimated >1,100 unique operational taxonomic units, most of which were from the monimolimnion, and the summer samples were more diverse than the fall samples (Chao1 = 530 and Chao1 = 295, respectively). For both seasons, the mixolimnion sequences were dominated by Gammaproteobacteria, and the chemocline and monimolimnion libraries were dominated by members of the low-G+C-content group, followed by the Cytophaga-Flexibacter-Bacteroides (CFB) group; the mixolimnion sediments contained sequences related to uncultured members of the Chloroflexi and the CFB group. Community overlap and phylogenetic analyses, however, not only demonstrated that there was a high degree of spatial turnover but also suggested that there was a degree of temporal variability due to differences in the members and structures of the communities.
* Corresponding author. Present address: Department of Forest Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada. Phone: (604) 822-8823. Fax: (604) 822-9102. E-mail: dimitriu{at}interchange.ubc.ca
Published ahead of print on 13 June 2008.
Supplemental material for this article may be found at http://aem.asm.org/.
Applied and Environmental Microbiology, August 2008, p. 4877-4888, Vol. 74, No. 15
0099-2240/08/$08.00+0 doi:10.1128/AEM.00455-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.
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