Economic importance of bacteria are used, too, to form organic acids in pickles and vinegar. Biotechnology bacteria the use of microorganisms including bacteria and fungi in the manufacturing and services industries. These include chemical manufacturing such as ethanol, acetone, organic acid, enzymes, and perfumes. In the chemical industry, bacteria are most important in the production of pharmaceuticals. "Escherichia coli" is used for commercial preparation of riboflavin and vitamin K. Genetic engineering is the manipulation of genes. It is also called recombinant DNA technology. In genetic engineering, pieces of DNA (genes) are introduced into a host by a variety of techniques, one of the earliest
Bacteria sizes, called morphologies. Bacterial cells are about one-tenth the size of eukaryotic cells and are typically 0.5–5.0 micrometres in length. However, a few species are visible to the unaided eye—for example, "Thiomargarita namibiensis" is up to half a millimetre long and "Epulopiscium fishelsoni" reaches 0.7 mm. Among the smallest bacteria are members of the genus "Mycoplasma", which measure only 0.3 micrometres, as small as the largest viruses. Some bacteria may be even smaller, but these ultramicrobacteria are not well-studied. Most bacterial species are either spherical, called "cocci" ("sing". coccus, from Greek "kókkos", grain, seed), or rod-shaped, called "bacilli" ("sing". bacillus,