Thiobacillus ferrooxidans cells grown on sulfur, pyrite, and chalcopyrite exhibit greater hydrophobicity than ferrous ion-grown cells. The isoelectric points of sulfur-, pyrite-, and chalcopyrite-grown cells were observed to be at a pH higher than that for ferrous ion-grown cells. Microbe-mineral interactions result in change in the surface chemistry of the organism as well as that of the minerals with which it has interacted. Sulfur, pyrite, and chalcopyrite after interaction with T. ferrooxidans exhibited a significant shift in their isoelectric points from the initial values exhibited by uninteracted minerals. With antibodies raised against sulfur-grown T. ferrooxidans, pyrite- and chalcopyrite-grown cells showed immunoreactivity, whereas ferrous ion-grown cells failed to do so. Fourier transform infrared spectroscopy of sulfur-grown cells suggested that a proteinaceous new cell surface appendage synthesized in mineral-grown cells brings about adhesion to the solid mineral substrates. Such an appendage was found to be absent in ferrous ion-grown cells as it is not required during growth in liquid substrates.
8 Figures and Tables
TABLE 1. Hydrophobic interaction chromatography of T. ferrooxidans grown on different substrates
FIG. 1. Hydrophobicity of T. ferrooxidans grown on ferrous ion (+), sulfur (0), pyrite (x), and chalcopyrite (E) by partitioning in n-hexadecane and aqueous phase. OD, optical density.
FIG. 2. Electrophoretic mobilities of T. ferrooxidans cells grown on ferrous ion (0), sulfur (-), pyrite (0), and chalcopyrite (0).
TABLE 2. ELISA readings for T. ferrooxidans grown on different substrates
FIG. 3. Electrophoretic mobilities of sulfur before interaction with T. ferrooxidans (0) and after interaction with T. ferrooxidans for 1 h (0), 24 h (0), 120 h (A), and 240 h (V).
FIG. 4. Electrophoretic mobilities of pyrite before interaction with T. ferrooxidans (0) and after interaction with T. ferrooxidans for 1 h (0), 24 h (0), 120 h (A), and 240 h (V).
FIG. 5. Electrophoretic mobilities of chalcopyrite before interaction with T. ferrooxidans (0) and after interaction with T. ferrooxidans for 1 h (0), 24 h (C), 120 h (A), and 240 h (V).
FIG. 6. FTIR difference spectra obtained by subtracting the spectra of ferrous ion-grown T. ferrooxidans cells from those of sulfur-grown cells.
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