Identification of Thiobacillus bacteria in agricultural soil in Iran using the 16S rRNA gene

Thiobacillus, as useful soil bacteria, plays an important role in sulfur cycling. The purpose of this study was to identify the species Thiobacillus thioparus, Thiobacillus novellas and Thiobacillus denitrificans in rainfed and irrigated lands soil in Ajabshir, Ilam, Qorveh, Rojintaak, Sonqor, Kermanshah and Research Farm of Razi University in Iran. Sampling was performed as randomized completely with three replications at depth of 0–30 cm. The Thiobacillus species were determined via 16S rRNA characteristics. The results of agarose gel electrophoresis indicated that T. thioparus was the highest amount in the irrigated land in Research Farm and its lowest amount was in the Rojintaak rainfed land. These species not found in four locations and conditions including the Ajabshir irrigated, Qorveh rainfed, Research Farm rainfed and Rojintaak irrigated lands. The results of the T. novellas indicated that this was found in Ilam irrigated, Qorveh rainfed, Research Farm irrigated, Rojintaak irrigated and Rojintaak rainfed lands. The highest and lowest amount of T. novellas was indicated in the Rojintaak and Ilam irrigated lands respectively. The T. denitrificans gene showed that this bacterium was observed only in both samples of Ajabshir. Our study showed that Thiobacillus was not detected in all of the soils. If sulfur fertilizer is given to the soil without this bacterium, it is necessary to use sulfur fertilizer with Thiobacillus bacteria inoculation for better sulfur oxidation.