|Chee Sanford, Joanne|
Submitted to: Microbial Ecology International Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 5/8/2006
Publication Date: 8/20/2006
Citation: Chee Sanford, J.C., Sanford, R.A., Loffler, F.E., Thomas, S.H., Sims, G.K. 2006. Investigating anaerobic microbial processes in agricultural soils using Anaeromyxobacter dehalogenans as a cosmopolitan model [abstract]. International Society for Microbial Ecology. 11:2025.
Technical Abstract: Anaerobic microbial processes have not been thoroughly studied in agricultural soils. Yet, anaerobic conditions may significantly impact agrochemical fate, nutrient cycling, and plant/seed-microbe interactions. As part of a broader weed ecology/weed management experimental program we have selected a network of agricultural sites in Illinois with different soil types and climates to study these anaerobic processes. Our experimental objective is to characterize the spatiotemporal anaerobic fate of herbicides, N2O, weed seeds, and plant residues in soil as a long-term microbial observatory. We will use Anaeromyxobacter dehalogenans, a spore-forming soil bacterium as a cosmopolitan model. This bacterium possesses diverse respiratory metabolisms, such as halorespiration of herbicides, ferric-iron reduction, ammoniafication, and N20 reduction. While Anaeromyxobacter is widespread in nature and physiologically well-characterized, it has not been specifically investigated in the context of important anaerobic agroecosystem processes. Our objective is to understand these processes in soils by using molecular-based approaches that target key populations and metabolic genes. Using PCR, we detected A. dehalogenans in 18 of 24 soil samples from the observatory network. Cloned 16S rRNA gene sequences had identities of 94-97% to Anaeromyxobacter. Using the same DNA, only atrazine degradation genes trzDN and atzBC were primarily detected. This suggests other functionally active atrazine degradation genes may be present. In a separate experiment with these soils, Anaeromyxobacter was detected in populations associated with velvetleaf seed surfaces, along with other Myxococcales. The results confirm that A. dehalogenans, related organisms, and specific gene targets will be useful in characterizing anaerobic agricultural soil processes in our observatory.