Abstract


THE OBSERVER EFFECT: QUANTIFYING THE IMPACT OF THE ACETYLENE REDUCTION ASSAY ON MARINE SEDIMENT N-FIXERS

Direct measurements of N-fixation rates are notoriously difficult. As such, for the last five decades we have relied on the simple and relatively easy acetylene reduction assay (ARA) to measure N-fixation. However, exposure to acetylene is known to cause numerous artifacts in other microbial processes including blocking aerobic nitrification and nitrous oxide reduction during denitrification. We examined the impact of ARA on the active sediment microbial community in sediments from a temperate estuary (Narragansett Bay, RI). We found that ARA significantly alters the total active microbial community composition. Additionally, preliminary RT-qPCR evidence shows the activity of N-fixers decreases with ARA treatment. Our results demonstrate that ARA may reduce N-fixation. Thus, rates of marine sediment N-fixation may actually be much higher than previously realized, and other direct methods may provide a more realistic rate measurement. Furthermore, because this assay is used to quantify N-fixation in ocean water columns as well as terrestrial and freshwater systems, our results suggest these values may also need to be re-evaluated.

Authors

Fulweiler, R. W., Boston University, USA, rwf@bu.edu

Newell, S. E., Boston University, USA, sen@bu.edu

Heiss, E. M., Boston University, USA, emheiss@bu.edu

Rogener, M. K., University of Georgia, USA, mkr@uga.edu

LeCleir, G. R., University of Tennessee, USA, glecleir@utk.edu

Wilhelm, S. W., University of Tennessee, USA, wilhelm@utk.edu

Details

Oral presentation

Session #:024
Date: 5/22/2014
Time: 15:00
Location: E 145 - 146

Presentation is given by student: No