L-Tryptophan Sector Urgently Needs Breakthroughs in Low-Cost Technologies   

By Xu Qingyang  

Tryptophan is the third major feed-grade amino acid, after methionine and lysine. It has also gained extensive applications in pharmaceutical, cosmetic, food and health product sectors in recent years. In 2009 the global output of L-tryptophan was reportedly around 4 000 tons. The consumption proportion was 20% for medicines, 30% for food and 50% for feed.
   China consumes around 300 tons of tryptophan a year. It is mainly used in pharmaceutical and food sectors. As L-tryptophan producers here have made no breakthroughs yet in reducing the production cost, the high price of domestic products has led to extremely little use of L-tryptophan in food and feed additives. With impacts from the drastic price rise of tryptophan in the European market, tryptophan producers and importers in China have increased the product price here by different degrees. The price of tryptophan in the domestic market has therefore increased. The market price of imported products is RMB220-230 per kg today. As the output of tryptophan in China is quite small, most products are directly sold by producers themselves and the market price of domestic products is also RMB200-220 per kg.
   With the constant development of the breeding sector, the demand for feed additives in China will increase. It is expected that the output of various feed additives in China will reach 3.0 million tons in 2010 and the demand for tryptophan in the feed market will be more than 1 500 tons. Besides, the demand in the pharmaceutical sector will also increase. The demand for tryptophan in the domestic market is expected to be around 1 000 tons a year and there will be a huge supply shortage.
   Tryptophan producers with commercial capacity in China include Hangzhou Hengrui Biological Products Co., Ltd. and the Jiayuan Chemical Co., Ltd. of Zhejiang Dongyang Hengdian Group. Hangzhou Hengrui Biological Products Co., Ltd., established in 2001, manufactures D-tryptophan, DL-tryptophan and L-tryptophan, with a combined capacity of around 12 t/a. L-tryptophan produced by Jiayuan Chemical Co., Ltd. was put into the state key new product plan list by the Ministry of Science and Technology in 2003. High-purity L-tryptophan produced by the company through a genetically engineered enzyme process is already being sold as commodity. The 150 t/a L-tryptophan project launched by CAS Institute of Microorganisms in collaboration with Hubei Bafeng Pharmaceutical & Chemical Co., Ltd. has already been launched. Enzymatic synthesis will be conducted from L-tryptophan precursor pyruvic acid with the addition of indole and ammonia. Shanghai FiRo Bioengineering and Technology Co., Ltd. has invented a microbial conversion process to produce L-tryptophan and the conversion rate and the yield have reached 95% and 65% respectively. Besides, some enterprises in Shanghai, Wuhan, Hubei and Beijing also make the small-scale production of tryptophan mainly for the use in medicines. It is reported that under the guidance of Prof. Chen Ning from Tianjin University of Science and Technology, the Henan Julong Starch Industry Co., Ltd. has successfully completed pilot tests on the production of L-tryptophan through direct fermentation. The company plans large-scale production with a capacity of 500 t/a. It is expected that with joint efforts the tryptophan sector in China will quickly enter an epoch of low cost and large-scale production.