title: Preliminary Study on Cost-Effective L-Tryptophan Production from Indole and L-Serine byE. coliCells.
abstract: BACKGROUND
  L-tryptophan is used widespread in the pharmaceutical industry. The majority of L-Trp production depends on microbial processes that produce L-tryptophan from indole and L-serine. These processes are very costly due to the costs of precursors, especially L-serine. Use of inexpensive substitutions as the L-serine source of L-tryptophan production enables us to reach a cost-effective process. In this paper, effect of Triton X-100 on L-Trp production and the ability to use Iranian cane molasses as inexpensive L-serine source was investigated.
  
  
  METHODS
  Escherichia coli (E. coli) ATCC 11303cells were grown in 10-L fermenter containing minimal medium supplemented with beet molasses as an inexpensive carbon source and indole as tryptophan synthase inducer. Whole cells of stationary phase were used as biocatalyst for L-Trp production. Triton X-100 addition to the production medium as indole reservoir was investigated. Then, cane molasses was used as L-Ser source in L-Trp production medium. Amount of L-Tryptophan and theoretical yield of L-Trp production was determined by HPLC and by a colorimetrically method on the basis of remaining indole assay, respectively.
  
  
  RESULTS
  As a result, triton X-100 increased L-Trp production three times. Also, the result showed that 0.68mML-Tryptophan was produced in the presence of cane molasses at 37°Cfor 8hr.
  
  
  CONCLUSIONS
  This result showed that cane molasses of Qazvin sugar factory includes significant amounts of L-Ser that makes it a suitable substitution for L-Ser in L-Trp production. Therefore, it has the potential to be used for cost-effective L-Trp production in industrial scale.
authors.affiliation: Department of Pharmaceutical Biotechnology, Faculty of Pharmacy, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Tahereh
authors.initials: T
authors.lastname: Sadeghiyan-Rizi
authors.affiliation: National Laboratory of Industrial Microbiology, Department of Biology, Faculty of Science, Alzahra University, Tehran, Iran.
authors.forename: Jamshid
authors.initials: J
authors.lastname: Fooladi
authors.affiliation: Department of Pharmaceutics, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Sima
authors.initials: S
authors.lastname: Sadrai
keywords: Molasses; PLP; Tryptophan synthase; Tryptophanase