The Attachment Behavior Of Three Bioleaching Strains With Different Energy Metabolism In The Initial Phase

This study is to investigate the difference in the attachment behavior of Acidithiobacillus ferrooxidans ATCC23270、 Acidithiobacillus thiooxidans A01and Leptospirillum ferriphilum YSK grown with different substrates as energy sources on elemental sulfur, quartz and complex chalcopyrite in the initial phase. And we also tried to find the relationship between attachment behavior and the surface properties of cells and adsorbents. The attachment equilibrium datas were plugged into Langmuir and Freundlich equation with linear fitting. And fitted parameters of two equations were used to study the difference in attachment behavior of different cells. Meanwhile, the surface properties of cells and substrates were investigated by using FT-IR, MATS and Zeta potential. And extracellular polymeric substances were extracted from cells with ultrasonic method in order to explore the difference in extracellular polysaccharides and proteins in EPS and their effect for bacterial attachment.The results indicated that the number of adsorbed cells of A. ferrooxidans ATCC23270, A. thiooxidans A01and L. ferriphilum YSK on three adsorbent surfaces increased over time. In the first ten-minute of bacterial-adsorbent contact, the adsorption rate was considerably greater than the desorption rate. The attachment of three strains grown with different energy sources attained equilibrium within different time but no more than60min.The net electrical charge on the cells surfaces was negative and decreases with pH from2.0to8.0. Most cells showed a zeta potential close to zero at pH2.0. So the faint electrostatic action existed in interaction between cells and adsorbents. Elemental Sulfur-grown strains exhibited the highest hydrophobicity, followed by complex chalcopyrite-grown strains and Fe2+-grown strains.Two equations could successfully fit the attachment equilibrium datas with significant correlation coefficient over0.90. This indicated bacterial attachment onto three solid substrates was complicated and involved Langmuir and Freundlich model characterization including monolayer homogeneous attachment and multilayer uneven attachment. This is a good addition to bacterial attachment in the early stage. A significant difference was observed in the attachment behavior of cells grown with different energy. The same strain grown with different energy exhibited a different affinity for three adsorbents. Elemental sulfur-grown cells exhibited a higher affinity for three adsorbents than Fe2+-grown and complex chalcopyrite-grown cells. There is a difference in adsorption affinity of the same cells for different adsorbents. Complex chalcopyrite-grown cells showed a significant difference in adsorption affinities for three adsorbents. And complex chalcopyrite provided more attachment sites for cells than elemental sulfur and quartz on their surface.