Vitamins and Amino Acids
Vitamins are used as supplements for human food and animal feeds, and production of vitamins is second only to that of antibiotics in total sales of pharmaceuticals.
Most vitamins are made commercially by chemical synthesis. However, a few are too
complicated to be synthesized inexpensively but can be made in sufficient quantities relatively easily by microbial processes.
Vitamin B12 and riboflavin are the most important of these vitamins. World production of B12 is on the order of 10,000 tons per year and of riboflavin about 1,000 tons per year