Master of Science (MS), Bowling Green State University, 2019, Biological Sciences

Chapter 1: Lake Vostok is named for the nearby Vostok Station located at 78°28'S, 106°48'E and at an elevation of 3,488 m. The lake is covered by a glacier that is approximately 4 km thick and comprised of 4 different types of ice: meteoric, basal, type 1 accretion ice, and type 2 accretion ice. Six samples were derived from the glacial, basal, and accretion ice of the 5G ice core (depths of 2,149 m; 3,501 m; 3,520 m; 3,540 m; 3,569 m; and 3,585 m) and prepared through several processes. The RNA and DNA were extracted from ultracentrifugally concentrated meltwater samples. From the extracted RNA, cDNA was synthesized so the samples could be further manipulated. Both the cDNA and the DNA were amplified through polymerase chain reaction. Ion Torrent primers were attached to the DNA and cDNA and then prepared to be sequenced. Following sequencing the sequences were analyzed using BLAST. Python and Biopython were then used to collect more data and organize the data for manual curation and analysis. Chapter 2: As a result of the glacier and its geographic location, Lake Vostok is an extreme and unique environment that is often compared to Jupiter's ice-covered moon, Europa. Lake Vostok was originally thought to be sterile, but multiple studies have suggested that not only is there a variety of bacterial and eukaryotic organisms living in the lake, but it may contain a complex ecosystem. The results of this analysis yielded metagenomic and metatranscriptomic data that aligned with a wide variety of organisms from 30 different phyla. The associated organisms were capable of many metabolic pathways, such as the nitrogen cycle and carbon fixation, as well as oxidation and/or reduction pathways for sulfur, iron, arsenic, hydrogen, hydrocarbon, phosphorous, uranium, and chromium compounds. The number of organisms unique to each sample was quite high for all samples except the layered meteoric ice sample, which only contained sequences similar to one organism. These results, (open full item for complete abstract)

Committee: Scott Rogers Ph.D (Advisor); Helen Michaels Ph.D (Committee Member); Paul Morris Ph.D (Committee Member) Subjects: Bioinformatics; Biology; Microbiology; Molecular Biology; Paleoecology

Doctor of Philosophy, The Ohio State University, 2002, Graduate School

Committee: Not Provided (Other) Subjects: Biology

Doctor of Philosophy (Ph.D.), Bowling Green State University, 2015, Biological Sciences

Abstract: Lake Vostok (Antarctica) is the 4th deepest lake on Earth, the 6th largest by volume, and 16th largest by area, being similar in area to Ladoga Lake (Russia) and Lake Ontario (North America). However, it is a subglacial lake, constantly covered by more than 3,800 m of glacial ice, and has been covered for at least 15 million years. As the glacier slowly traverses the lake, water from the lake freezes (i.e., accretes) to the bottom of the glacier, such that on the far side of the lake a 230 m thick layer of accretion ice collects. This essentially samples various parts of the lake surface water as the glacier moves across the lake. As the glacier enters the lake, it passes over a shallow embayment. The embayment accretion ice is characterized by its silty inclusions and relatively high concentrations of several ions. It then passes over a peninsula (or island) and into the main basin. The main basin accretion ice is clear with almost no inclusions and low ion content. Metagenomic/metatranscriptomic analysis has been performed on two accretion ice samples; one from the shallow embayment and the other from part of the main lake basin. Ice from the shallow embayment contains a variety of Bacteria as well as a few Archaea and several types of Eukarya. Most are related to species that are psychrophilic, marine, aquatic, or live in lake/ocean sediments, or a combination of these. However, sequences identified as originating from many different thermophiles were found, suggesting the presence of hydrothermal activity in the lake. In contrast to the embayment ice, the ice from the main basin yielded only about 5-6% of the number of sequences. Here again, molecular signatures of psychrophiles, marine, aquatic, a few sediment-dwelling organisms, and a few thermophiles were found. Because of the extreme conditions, it has been hypothesized that Lake Vostok is sterile, or that very few types of organisms inhabit the lake. Our results indicate that it contains a diverse (open full item for complete abstract)

Committee: Scott O. Rogers Dr. (Advisor); Paul F. Morris Dr. (Committee Member); Vipaporn Phuntumart Dr. (Committee Member); Robert Michael McKay Dr. (Committee Member); Rober W. Midden Dr. (Other) Subjects: Bioinformatics; Biology; Ecology; Limnology; Molecular Biology

Doctor of Philosophy, The Ohio State University, 2002, Microbiology

An extraction system has been constructed that melts ice from the interior of ice cores and collects the resulting melt water aseptically. Using this system, bacteria entrapped in modern and ancient glacial ice from worldwide locations and in an ice core extending into accreted Lake Vostok ice have been isolated using enrichment culture and identified by amplification and sequencing of DNA-encoding 16S rRNA genes. In general, ice cores from non-polar locations contained larger numbers and species of cultivable bacteria than samples from polar ices, presumably due to the closer proximity of terrestrial biological ecosystems and exposed landscape. When compared with other polar locations, higher numbers of isolates were obtained from ices adjacent to the Dry Valley complex of Antarctica, consistent with the influx of airborne biological particles from local environments serving as the primary factor controlling the numbers of microorganisms present. The numbers of recoverable bacteria did not correlate directly with the age of the ice, and isolates were recovered from the oldest samples examined (>500K years old). The 16S rDNA sequences from bacterial isolates and amplicons obtained directly from samples position within 6 different bacterial lines of descent (alpha, beta, and gamma-proteobacteria, high and low G+C gram positive bacteria, and the Cytophaga/Flavobacterium/Bacteroides). Some of the isolated bacteria have close phylogenetic relationships with species originating from permanently cold environments, and other ice core sites or different portions (time periods) of the same core. Macromolecular synthesis was demonstrated in bacteria frozen under conditions analogous to those in glacial ice, and the possibility exists that metabolic activity and repair may occur during extended periods of glacial entrapment. Several of the species identified in Lake Vostok accretion ice are also related to glacial isolates and species from other cold environments. These ice co (open full item for complete abstract)

Committee: John Reeve (Advisor) Subjects: Biology, Microbiology

Doctor of Philosophy (Ph.D.), Bowling Green State University, 2009, Biological Sciences

The objective of this research was to study the bacterial and fungal composition of icecores from Arctic and the Antarctic regions to understand their geographical and temporal distribution. Cosmopolitan microbes dominate these environments and have been deposited primarily by winds, birds, Ocean currents and mammals. Atmospheric currents play a significant role in the transport of these microorganisms to the polar regions. We hypothesize that the geographical isolation of the Antarctic region from other land masses, compared to the Arctic region, affects the transport of the microorganisms to the Antarctic region, resulting in lower number of microbes entrapped in the Antarctic ice. Four ice cores each were analysed from the Arctic (GISP2D core) and the Antarctic (Vostok 5G core) regions dating back to 10,000 YBP, 57,000 YBP, 105,000 YBP and 155,000 YBP using culturing, PCR, sequencing and SEM techniques. We report the isolation of fungi and bacteria from six of the eight ice cores analysed. Fungi most closely related to Rhodotorula, Penicillium, Cladosporium, Alternaria, Aspergillus and Cryptococcus, and bacteria related to Caulobacter and Bacillus were identified. The ice cores from Arctic had higher number of microorganisms and species richness than the core sections from the Antarctic region. Phylogenetic studies were done to compare the organisms with one another and also with the conspecifics. Some sequences showed high similarity to contemporary species, while some did not group closely with the present day organisms. Fungi isolated from the different locations, and closely related to the same genus, did not show high similarity with one another.

Committee: Scott Rogers (Advisor); Kurt Panter (Committee Chair); Carmen Fioravanti (Committee Member); Vipaporn Phuntumart (Committee Member); John Castello (Committee Member) Subjects: Molecular Biology

Doctor of Philosophy (Ph.D.), Bowling Green State University, 2008, Biological Sciences

Lake Vostok, located below the 4000 m thick Antarctic Ice Sheet, is the largest subglacial lake in Antarctica. The lake water has not been sampled due to concerns of forward contamination. However, ice cores available from the Vostok 5G well of depths greater than 3538 m represent lake water that has accreted to the overhead glacier from various regions across Lake Vostok. Here, we report the characterization of bacteria and fungi from ten accretion ice sections (15,000 to 18,000 years old), and two deep glacial ice sections (1 to 2 million years old) from the Vostok, Antarctica 5G ice core. Fungi, as well as bacteria, were characterized by fluorescence microscopy, scanning electron microscopy, culturing, and sequence analyses of ribosomal DNA. A total of 703 bacteria and fungi were cultured from the accretion ice of subglacial Lake Vostok. Mean cell concentrations were from 2.3 to 12.3 cells per ml of ice meltwater, of which 5 to 84% were viable. These cell counts are substantially lower than previously reported values. A total of 54 unique ribosomal DNA sequences were determined and compared to recent taxa, of which 36 were fungi and 18 were bacteria. Fungi most closely related to Rhodotorula, Aureobasidium, Cryptococcus, Cladosporium and Penicillium, and bacteria related to Carnobacterium spp., Bacillus spp., Caulobacter and Micrococcus were identified based on sequence analysis from cultured isolates. These findings, plus tests for growth at low temperatures, indicate that Lake Vostok contains a mixture of heterotrophic psychrotolerant and psychrophilic species. The results revealed new genera of microorganisms not previously reported in Lake Vostok accretion ice, lower abundances of microorganisms, and demonstrated the necessity to use multiple methods to thoroughly characterize environmental ice.

Committee: Scott Rogers PhD (Advisor); George Bullerjahn PhD (Committee Member); R. Michael McKay PhD (Committee Member); Paul Morris PhD (Committee Member) Subjects: Biology; Ecology; Microbiology; Molecular Biology