Metal removal by Acidithiobacillus ferrooxidans through cells and extra-cellular culture supernatant in biomachining

This study explores an innovative metal machining process by using bacteria. Acidithiobacillus ferrooxidans (At. ferrooxidans) was used to remove metal. The bacteria first carried out the oxidation of Fe2+ to Fe3+. The produced Fe3+ then oxidized the metals. The machining of copper, nickel and aluminum was experimentally investigated using both the cells and the culture supernatant of At. ferrooxidans. The material removal rates of these three metals were 2.0, 1.6, 0.55 and 5.5, 4.2 and 0.7 mg/h cm2 by using cells and culture supernatant, respectively. Higher metal removal rate was achieved for copper by using the culture supernatant. A microbe-based fabrication of micropattern is thus feasible applying the current principle.