Analysis of microbes in Greenland ice cores from periods of high and low atmospheric carbon dioxide levels

Glacial ice entraps microbial cells and nucleic acids that have been deposited from the atmosphere by precipitation or on dust particles carried by the wind. The ice is deposited in sequential layers representing distinct past periods of time. Metagenomics and metatranscriptomics offer means to perform comprehensive analyses of microbial genes and taxa within the ice. During the past 400,000 years, fluctuations in atmospheric carbon dioxide levels have directly coincided with temperature fluctuations. Three ice core sections from Byrd Station, Antarctica (80° 1’ S, 119° 31’ W) and three ice core sections from GISP 2D (Greenland Ice Sheet Project, core 2D; 72o 36' N, 38o 30'W) were aseptically melted. Two of the ice core sections from GISP 2D (at 1600 m = 10,500 ybp [years before present] and at 3014 m = 157,000 ybp) were analyzed using metagenomic and metatranscriptomic analyses. The 157,000 year old ice core section was deposited during low atmospheric CO2 levels that would have led to low temperatures, low precipitation rates, and high dust levels, while the 10,500 year old core section was deposited during high CO2 levels that would have led to higher temperatures, higher precipitation rates, and lower dust levels. Nucleic acids from ultracentrifuge-concentrated meltwater were subjected to 454 pyrosequencing. Taxonomic analyses were based on rRNA and mRNA sequences. Taxa in the 10,500 ybp ice primarily included bacterial species of Proteobacteria, Firmicutes, and Cyanobacteria. This sample also contained black particulate matter indicative of volcanic activity. Major volcanic activity was reported in Iceland, Alaska, and from a super volcano in Italy during the 10,500 ybp time period. The 157,000 ybp sample also contained a large number of Proteobacteria and Firmicute species, a few Actinobacteria and Cyanobacteria, but most were common soil bacteria, as well as animal pathogens. The number and frequency of cyanobacterial species was much higher. While some species were in common to both samples, a large number of unique taxa and genes were present in each of the samples. These unique taxa and genes suggest different atmospheric conditions may influence the deposition of microbes in ice.

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Biological Sciences

Grantor dc:publisher

Bowling Green State University

Year dc:date

2013

Author dc:creator

• Knowlton, Caitlin N.

Contributors dc:contributor

• Rogers, Scott

• Microbiology
• Molecular Biology
• Bioinformatics
• glacial ice
• Greenland
• metagenomic
• metatranscriptomic
• microbes
• bacteria
• carbon dioxide

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1362670626

OAI identifier oai:identifier

oai:etd.ohiolink.edu:bgsu1362670626