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Molecular and Cultivation-based Characterization of Ancient Algal Mats from the McMurdo Dry Valleys, Antarctica

Antibus, Doug E.

Abstract Details

2009, MS, Kent State University, College of Arts and Sciences / Department of Biological Sciences.
The McMurdo Dry Valleys in Antarctica present an opportunity for viable bacteria and bacterial DNA to be preserved over millennial-scale periods of dormancy because 1) the cold and dry climate of the Dry Valleys favors preservation of biological materials and 2) many Antarctic microbes are adapted to withstand stresses resulting from long periods of dormancy. Because of this potential for microbial preservation, the Dry Valleys may be the recipients of a legacy of genetic diversity dating from the Holocene, when the valleys were occupied by glacial lakes, although this possibility has not been previously investigated.This study examined samples of algal mat from the McMurdo Dry Valleys representing a chronological sequence in 14C age from 8 to 26,539 years before present. Research focused on the recovery of bacterial DNA and the examination of bacterial diversity by bacterial 16S rRNA gene clone libraries, as well as the recovery of cultivable bacteria from the samples. Bulk DNA abundance, bacterial DNA integrity, and the abundance and diversity of cultivable bacteria all declined with increasing sample age, matching expected patterns for ancient materials. Clone sequences belonging to the Cyanobacteria were abundant in a modern sample but absent from ancient samples. In contrast, Firmicutes 16S rRNA gene sequences and cultivable Firmicutes were abundant in ancient samples. The abundance of Firmicutes supports the inference that bacterial gene sequences and cultivable bacteria from samples were authentically ancient, as Firmicutes are not common in Antarctic soils. Additionally, anaerobe sequences were abundant in clone libraries, which would be expected for Antarctic algal mats rather than mineral soils. BOX-PCR genotyping was applied to 105 isolates belonging to the Firmicutes genus Sporosarcina from ancient and modern samples. Previous research in the McMurdo Dry Valleys has found that highly similar 16S rRNA gene sequences are distributed throughout the landscape, suggesting that alpha and gamma richness of bacterial species are similar. In this study, little overlap of Sporosarcina genotypes between samples was observed, suggesting that gamma richness of genotypes is greater than alpha richness. Isolates displayed differential responses to growth temperature, which was associated with BOX-PCR genotype. Genotypes were also unevenly distributed over temperature and medium treatments used in initial cultivation attempts, suggesting that genotypes are adapted to different substrate and temperature conditions.
Christopher Blackwood (Advisor)
Laura Leff (Committee Member)
Christopher Woolverton (Committee Member)
135 p.

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Citations

  • Antibus, D. E. (2009). Molecular and Cultivation-based Characterization of Ancient Algal Mats from the McMurdo Dry Valleys, Antarctica [Master's thesis, Kent State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=kent1258702723

    APA Style (7th edition)

  • Antibus, Doug. Molecular and Cultivation-based Characterization of Ancient Algal Mats from the McMurdo Dry Valleys, Antarctica. 2009. Kent State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=kent1258702723.

    MLA Style (8th edition)

  • Antibus, Doug. "Molecular and Cultivation-based Characterization of Ancient Algal Mats from the McMurdo Dry Valleys, Antarctica." Master's thesis, Kent State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=kent1258702723

    Chicago Manual of Style (17th edition)