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Title:Expression of dsr messenger RNA by sulfate reducing bacteria with varying substrate and temperature
Author(s):Farrell, Brian M.
Advisor(s):Bethke, Craig M.; Sanford, Robert A.
Department / Program:Geology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Microbial sulfate reduction
Gene expression
Abstract:Recent studies raised the possibility of estimating the activity of sulfate reducing bacteria by measuring the number of messenger RNA (mRNA) transcripts of dsr, a critical gene in the sulfate reduction pathway, in a cell. Because conditions in aquifers can be quite different from those maintained in laboratory experiments, it is unknown whether the results of such studies can be applied to field settings. We test whether dsr expression is dependent on electron donor and incubation temperature, commonly observed variables known to affect reaction rates. We compare results using formate, an electron donor found in pristine aquifers, to lactate and ethanol, substrates commonly used in laboratory experiments and field biostimulation projects, but largely absent in nature. Incubation temperatures of 18°C, 23°C, and 30°C were used to determine the effect of temperature on dsr expression. From reactors in which we fixed rates of sulfate reduction, we extracted nucleic acids and measured biomass, then used quantitative PCR to measure the number of transcripts of dsr mRNA per cell. We find a clear relationship between dsr expression and the rate of sulfate reduction per cell. Considering the difficulty involved in determining sulfate reduction rates in aquifers using other techniques, dsr expression may provide a useful estimate of activity under a range of environmental conditions.
Issue Date:2011-08-25
Rights Information:Copyright 2011 Brian M. Farrell
Date Available in IDEALS:2011-08-25
Date Deposited:2011-08

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