Bacterial diversity assessment of highly complex soil environments using multi-million read generating sequencing technologies.

Soil biogeochemistry domination by Bacteria has driven towards intensive studying of their diversity in such environments. Although the breakthrough of the small ribosomal subunit (SSU) coding gene usage as a molecular marker increased throughput in bacterial diversity studies, it was soon indicated that complex soil environment requirements superseded potentials of past sequence based SSU screening methodologies. Recent high throughput sequencing technologies provided a solution in regards with read numbers but have restrictions concerning analyzed sequence lengths. Aim of the present study was to assess the information potentials according to the multi-million read depths and the SSU single hypervariable (V) region screening limitations provided by novel sequencing technologies for soil environments. V region analysis included database exploration and in silico analysis of literature based generated data. Moreover, samples screened with the referred strategy and were derived from soils that differed in properties due to land use and management, comprised a “real-world” reference for the method application evaluation. Database and in silico analysis indicated that the overall most prominent V region for soil bacterial diversity studies was V3. Soil derived data analysis provided detailed core microbial assemblage (microbiome) comparisons between Illumina screened soils, showing management correlated differences. Resolution abilities also made possible to examine diversity drivers and ecology theory application potentials in the highly complex soil environments used in the present study. Results of this study summarize the reasons according which technologies providing multi- million read sequencing depths are expected to dominate bacterial diversity screening studies during oncoming years.