Strategies Influencing Spatial Heterogeneity of Microbial Life in a Soil Lysimeter.

Soil microorganisms are critical components driving the biological processes, and have a profound impact on landscape stability. These microbes, in conjunction with their physical and chemical environment, contribute to ecosystem functioning and services of the landscape, and are of particular importance in oligotrophic environments; ecosystems that are characterized by low biotic diversity due to extremely low nutrient levels. Whereas microorganisms in well-developed soils are found in great abundance and diversity, there is a knowledge gap pertaining to 1) the spatial heterogeneity of microbes over a new and evolving landscape with inherent oligotrophic conditions, and 2) the significance of these organisms as drivers of weathering and landscape formation processes. Here, we present an intensive study to capture microbial heterogeneity in a soil lysimeter. We hypothesized that stratification of environmental conditions, brought about by varying water potential, flow paths, and redox conditions, will drive the heterogeneity of microbial life in a scale as small as 10cmx20cmx10cm. The lysimeter was filled with crushed basaltic tephra of volcanic origin and subjected to episodes of rain. The lysimeter was intensively excavated into smaller voxels. The DNA extracted ranged from those below detection limit to a maximum of 30 ng/g soil. A suite of traditional and current microbiological tools were employed to study community characteristics. These included isolation on R2A media, quantitative polymerase chain reactions targeted at 16S rRNA bacterial and archaeal genes, and iTAG phylogenetic gene amplification. Alongside physical and chemical data, we will present patterns observed in spatial heterogeneity of microbes, and predict strategies undertaken by these microbes to survive in, and influence their oligotrophic environments.