Influence of Soil Physical Gradients in Spatial Distribution of Bacterial Communities; A Field Scale Study about Soil Inner Space Biology.

Bacterial influence in soil complexity, diversity and vastness is quite significant. They hold the key for soil sustainably and functionality. Biotic and abiotic processes in soils are intimately related and interdependent, providing continuous feedback to each other. Therefore, understanding of soil physical phenomena that can influence bacterial community distribution may open up new avenues to define soil as biomaterial. Microbial community composition in the soil inner space can be visualized and measured with modern molecular biological fingerprinting techniques, especially nucleotide sequencing. Thus, this study was conducted to search for evidence of interactions between bacterial communities and soil physical gradients. A cross-disciplinary approach was taken to link physics and biology in soil inner space. Soil textural and structural parameters and moisture contents were determined at 60 evenly distributed sampling points. Bacterial community composition and diversity were concurrently determined at the sampling locations using 454 16S rDNA gene-amplicon sequencing. The bacterial community structure and its distribution significantly influenced by soil structural and textural gradients. Physical complexity of the soil matrix created by soil textural and structural gradients clearly controls the microenvironment for soil bacteria and thus soil bacterial distribution across the field.