Aspergillus Tubingensis Reduces the pH of the Bauxite Residue (Red Mud) Amended Soils

Bauxite residue (red mud), a poor substrate for plant growth because of very high pH, salinity and sodicity, is required to be revegetated. The possibility of using Aspergillus tubingensis (AT1), a phosphate solubilizer in red mud amended soils to reduce the alkalinity of the red mud was studied in the present study. A. tubingensis was tested for its ability to grow at high pH and in different concentrations of aluminium (Al), iron (Fe) and sodium (Na). The results showed that A. tubingensis was able to grow at high pH and reduce the alkalinity of the nutrient medium and also to accumulate different metals in the mycelium. The pH values of the red mud amended soils were also significantly reduced (by 2–3 units) by A. tubingensis, which resulted in maize growth improvement. These results suggest that A. tubingensis plays an important role in reducing the pH of the red mud and also helps in promoting the plant growth in it.