Biomachining-micromachining of metals by bacteria

The various material processing techniques presently in use can be broadly classified into two categories according to the energy used in the technique, which are physical processing and chemical processing. Natural science system is generally classified into three categories-physical, chemical, and biological. However, no bio-logical technique has ever been developed for material processing. The recent advances in biotechnology have led to the widespread application of its techniques in many fields. Thus, it appears desir-able to investigate the possibility of biological material processing techniques. Many kinds of microorganisms exit, some of whose ac-tions can be considered as a kind of material processing. If it is pos-sible formicroorganisms tomachine the desired part to the required depth, they can be useful as tools for micromachining. From the above-mentioned viewpoint, the possibility of biological machining of metals by a kind of lithotroph, Acidithiobacillus ferrooxidans, which lives in a specific environment, was investigated.