Isolation and characterization of Acidithiobacillus caldus TST3 and the effect of pre-cultivation on its dissolution of phosphorous from rock phosphates

The dissolution of rock phosphates by A. caldus TST3 was explored in a series of bio-leaching experiments without and with pre-cultivation of the microorganism. The results showed that phosphorous was more efficiently bio-solubilized under the condition without pre-incubation in comparison to that obtained with pre-cultivation when strain TST3 was cultured in a phosphorous-limited environment. The presence of RPs exerted a positive effect on the expression of sulfur oxidation genes, bio-oxidative activity of elemental sulfur and bacterial growth. Bio-solubilization of rock phosphates was a pH-dependent phenomenon. The larger amount of phosphorous dissolved from rock phosphates without pre-cultivation coincided with the increased generation of gypsum crystals due to the relatively lower pH values from the enhanced bio-oxidization of sulfur.