Characterization of Microbial Communities in Agroecosystems

Abstract

Substrate utilization and stress response patterns were assessed for bacteria, fungi, and actinomycetes in both wheat and prairie systems. Landscape position was also a potential source of variation among the samples. The data were further analyzed according to distinct isolate groupings. Bacterial isolates from the tilled systems had higher carbon source utilization as compared to prairie isolates, while actinomycetes isolates from the prairie system had higher carbon sources utilization as compared to the tilled system isolates. Overall, actinomycetes isolate responses were higher for both the tilled and prairie systems. Actinomycetes isolates also had the highest growth rates in the presence of stressors for both systems as compared to bacterial and fungal isolates. Microbial substrate utilization differed with landscape position. The isolates from the tilled system had higher substrate utilization from foot slope, while the isolates from the prairie system had higher substrate utilization responses from side slope. Ridge top responses were similar. Relationship analyses among the substrates, isolates, and management systems support these findings. Actinomycetes had strong associations with arginine, sorbitol, xylan, streptomycin, and penicillin. Investigations of this nature can provide insight into the unknown of functional diversity. By isolating individual subsets of the community, and monitoring their nutritional strategies and performance under stress, we can gain valuable information into responses from different management systems.