Biomachining rates of various metals by Acidithiobacillus thiooxidans

Abstract

The evaluation of a potential of a microorganism for the biomachining technology is conducted in the current study. As the fundamental step, the specific metal removal rates (SMRR) of copper, nickel and aluminium in use of different level of cell concentration of Acidithiobacillus thiooxidans(At. thiooxidans) and the associated supernatant are investigated and compared. The specific metal removal rate is a key criterion to characterise any industrial machining process. The dissolution of metals by this chemolithotrophic bacteriumcan occur either by direct or indirect mechanism. The extracellular supernatant showed higher machining rate than the cells in solution. The aspect ratio in micropattern machining is examined for copper and nickel. The behaviour of aluminium in micromachining was unsatisfactory. The scanning electron microscopy was used to analyse the surface of copper workpiece before and after oxidation. During the oxidation of copper the changes in surface appearance and surface roughness were observed.