SS2.04 Microbial Stoichiometry and Impacts on Biogeochemistry: From Genes to the Biosphere
Date: Friday, June 14, 2002
Time: 11:00:00 AM
Location: Carson C
WohlDL, University of Richmond, Richmond, USA,
Arora, S, , University of Richmond, Richmond, USA,
Huntington, A, L, Univeristy of Richmond, Richmond, USA,
Joseph, S, , University of Richmond, Richmond, USA,
Within biologically diverse communities, organisms perform overlapping functions. Understanding functional redundancy (defined as multiple species carrying out a single function) is essential to understanding the role of biodiversity. Ten functionally redundant bacterial species (i.e., cellulose degraders) were isolated from a lotic environment. We tested the hypothesis that as functional redundancy increases, the rate of the function (cellulose degradation) increases. Mixed assemblages (1, 2, 4 and 8 microbial strains) were constructed. Experimental runs were 25 days, sampled at 5 day intervals. Sterile microcosms, with 0.025 g cellulose as the only carbon source, were inoculated with a final density of 2.0 x 10^5 cells per ml regardless of species composition. On each date, measures of biomass, enzyme activity (glucopyranosidase, BETA-cellobiosidase and BETA-cellotriosidase), species diversity and rates of cellulose decomposition were recorded. Assemblages with more than two isolates had the greatest levels of enzyme activity and greatest rates of cellulose degradation between days 5 and 15. We also found that greater diversity led to the maintenance of diversity over time. These findings suggest that functional redundancy is an important element in ecosystem function.