Surface Hydrophobicity of an Acidophilic Heterotrophic Bacterium of Mine Origin under Metal Stress
Cell surface hydropobicity plays a significant role in microbe-mineral interactions with special relevance of bioleaching. The present investigation envisages a study on the hydrophobic character of Acidiphilium symbioticum KM2, an acidophilic strain of bioleaching environment, when grown in presence of heavy metals - copper, zinc, cadmium and nickel. The metals, at its sub inhibitory concentrations (MIC50), exhibited profound negative effect on the growth of the bacterium. Inhibition on the culture growth rate was highest due to cadmium followed by zinc, nickel and copper. However, upon successive adaptation in different concentrations of each metal in ascending order, the cells could grow rapidly in the presence of higher concentrations of the metals indicating good metal resistance by the bacterium. Compared to normally grown cells, A. symbioticum KM2, when grown in presence of the metals, became more hydrophobic, which was dependent on the metal and its concentration in the media. Among the four metals studied, the effect of copper was found to be the highest, where up to 74 % increase in the bacterial cell hydrophobicity was observed.
Axel Schippers, Wolfgang Sand, Franz Glombitza and Sabine Willscher
K. Pakshirajan "Surface Hydrophobicity of an Acidophilic Heterotrophic Bacterium of Mine Origin under Metal Stress", Advanced Materials Research, Vols. 20-21, pp. 362-365, 2007