Date of Graduation

12-2017

Document Type

Thesis

Degree Name

Master of Science in Cell & Molecular Biology (MS)

Degree Level

Graduate

Department

Cell & Molecular Biology

Advisor/Mentor

Ivey, D. Mack

Committee Member

Lessner, Daniel J.

Second Committee Member

McNabb, David S.

Third Committee Member

Erf, Gisela F.

Keywords

Astrobiology; Dissimilatory sulfite reductase; dsrAB; Exobiology; Mars; Sulfate reducers

Abstract

Numerous studies have tried to determine the survivability and proliferation of microorganisms under simulated Martian conditions. Furthermore, most of them have been focused on the ability of these microbes to cope with high brines’ salt (NaCl) concentrations inherent of the Martian surface. However, there are not studies related to the ability of bacteria to survive on subsurface environments that have increasing concentrations of sulfate compounds. For this research, a group of microorganisms known as sulfate-reducing bacteria or simply sulfate reducers were chosen due to their ability to use sulfate compounds as terminal electron acceptors to produce metabolic energy, their tolerance to low temperatures (psychrophilic microbes) and their anaerobic metabolism. Moreover, the principal purpose of this study was to determine the ability of sulfate reducers to carry active metabolism under conditions similar to those present on Mars subsurface (low temperature, high concentration of sulfate compounds, anoxic atmosphere-95% carbon dioxide, low nutrients availability, among others). Furthermore, we cultivated strains of Desulfotalea psychrophila, Desulfuromusa ferrireducens and Desulfotomaculum arcticum using different concentrations of minerals. The latter (CaSO4, MgSO4, FeSO4 and Fe2(SO4)3) are normally found as part of the Martian subsurface components and they can act as terminal electron acceptors in sulfate respiration. Moreover, PCR amplifications of the 16S rDNA gene and the dsrAB genes were performed in order to determine the growth and survivability of the three microorganisms tested. Finally, we were able to determine that they were metabolically active at the different types and mineral concentrations under study.

Download

Share

COinS