Biotech

Appl Microbiol Biotechnol (2005) 69: 1–8 DOI 10.1007/s00253-005-0155-y

MINI-REVIEW

Wolfgang Leuchtenberger . Klaus Huthmacher . Karlheinz Drauz

Biotechnological production of amino acids and derivatives: current status and prospects
Received: 13 June 2005 / Revised: 22 August 2005 / Accepted: 29 August 2005 / Published online: 30 September 2005 # Springer-Verlag 2005

Abstract Foralmost 50 years now, biotechnological production processes have been used for industrial production of amino acids. Market development has been particularly dynamic for the flavor-enhancer glutamate and the animal feed amino acids L-lysine, L-threonine, and L-tryptophan, which are produced by fermentation processes using highperformance strains of Corynebacterium glutamicum and Escherichia coli fromsugar sources such as molasses, sucrose, or glucose. But the market for amino acids in synthesis is also becoming increasingly important, with annual growth rates of 5–7%. The use of enzymes and whole cell biocatalysts has proven particularly valuable in production of both proteinogenic and nonproteinogenic L-amino acids, D-amino acids, and enantiomerically pure amino acid derivatives, which areof great interest as building blocks for active ingredients that are applied as pharmaceuticals, cosmetics, and agricultural products. Nutrition and health will continue to be the driving forces for exploiting the potential of microorganisms, and possibly also of suitable plants, to arrive at even more efficient processes for amino acid production.

Introduction
As the building blocks of life,amino acids have long played an important role in both human and animal nutrition and health maintenance (Bercovici and Fuller 1995). On account of its functionality and the special features arising from chirality, this class of compounds is biochemically
W. Leuchtenberger (*) Degussa-Stiftung, Bennigsenplatz 1, Düsseldorf, 40474, Germany e-mail: wolfgang.leuchtenberger@degussa.com Tel.:+49-6181-978573 Fax: +49-6181-907307 K. Huthmacher . K. Drauz Degussa AG, Rodenbacher Chaussee 4, Hanau-Wolfgang, 63457, Germany

extremely important and of great interest for the chemical industry (Leuchtenberger 1996). Of the 20 standard protein amino acids, the 9 essential amino acids-L-valine, L-leucine, L-isoleucine, L-lysine, L-threonine, L-methionine, L-histidine, L-phenylalanine, and L-tryptophanoccupy a key position in that they are not synthesized in animals and humans but must be ingested with feed or food. In terms of market volume, development over the last 20 years has been tremendously bullish in the so-called feed amino acids L-lysine, DL-methionine, L-threonine, and Ltryptophan, which constitute the largest share (56%) of the total amino acid market, estimated in 2004 atapproximately US $4.5 billion (Fig. 1). Also substantial is the share of the food sector, which is determined essentially by three amino acids: L-glutamic acid in the form of the flavorenhancer monosodium glutamate (MSG) and the amino acids L-aspartic acid and L-phenylalanine, both of which are starting materials for the peptide sweetener L-aspartyl Lphenylalanyl methyl ester (Aspartame), used, forexample, in “lite” colas. The remaining proteinogenic amino acids are required in the pharmaceutical and cosmetics industries and are also ideal raw materials for synthesis of chiral active ingredients, which in turn find application in such sectors as pharmaceuticals, cosmetics, and agriculture. According to a study by the Business Communication Company (Brown 2005), the amino acid market forsynthesis applications is growing at an annual rate of 7% and is expected to reach a volume of US $1 billion in the year 2009, of which the share of amino acids for peptide sweeteners alone is expected to be more than US $400 million.

Microbial amino acid production
The rapid development of the amino acid market since the 1980s is due in no small part to major successes in costeffective production...