An immunological strategy to monitor in situ the phosphate starvation state in Thiobacillus ferrooxidans

Thioliacillus ferrooxidans is one of the chemolithoautotrophic bacteria imp ortant in industrial biomining operations. During the process of ore biolea ching, the microorganisms are subjected to several stressing conditions, in cluding the lack of some essential nutrients, which can affect the rates an d yields of bioleaching. When T. ferrooxidans is starved for phosphate, the cells respond by inducing the synthesis of several proteins, some of which are outer membrane proteins of high molecular weight (70,000 to 80,000). T hese proteins were considered to be potential markers of the phosphate star vation state of these microorganisms, We developed a single-cell immunofluo rescence assay that allowed monitoring of the phosphate starvation conditio n of this biomining microorganism by measuring the increased expression of the the surface proteins. In the presence of low levels of arsenate (2 mM), the growth of phosphate-starved T. ferrooxidans cells was greatly inhibite d compared to that of control nonstarved cells. Therefore, the determinatio n of the phosphorus nutritional state is particularly relevant when arsenic compounds are solubilized during the bioleaching of different ores.