Bacterial community structure associated with oxidation of sulfuric soil materialâ€“ field experiment
Oxidation of sulfidic soil materials by sulfur and iron oxidating bacteria results in acidification and release of metals to the environment. Bacterial taxa or microbial mechanisms associated with the oxidation and environmental risk of the acid sulfate soils are not well understood especially in cold climate conditions. In this study, oxidation of sulfuric soil materials was followed in a field study using lysimeters that were filled with soil excavated from different depths of an acid sulfate soil containing site in Finland. The lysimeters contained carex peat, organic rich clayey silt, gravelly till, clayey silt and sandy till. Oxidation of sulfides was followed from both the soil and percolating water samples. Changes in the bacterial community structure was followed over two growing seasons by 16S rRNA gene amplicon sequencing.   The results demonstrated rapid oxidation of the sulfides as detected by a rapid and intensive acidification. This was coupled with rapid changes in the bacterial communities. Different sulfur and iron oxidating taxa became dominant in the different soil layers and at different times. The study revealed dynamic shifts in the bacterial communities during the oxidation and identified taxa important in the oxidation of acid sulfate soils in northern boreal ecosystems.