Cane molasses as a source of precursors in the bioproduction of tryptophan by Bacillus subtilis

BACKGROUND AND OBJECTIVES The essential amino acid L-tryptophan can be produced by a condensation reaction between indole and L-serine, catalyzed by B. subtilis with tryptophan synthase activity. Application of the tryptophan is widespread in the biotechnology domain and is sometimes added to feed products as a food fortifier. MATERIALS AND METHODS The optimum concentration of the Iranian cane molasses was determined by measuring the amount of biomass after growth in 1 to 30 g/mL of molasses. The maximum amount of biomass was obtained in 10 g/mL molasses. Chromatographic methods, TLC and HPLC, were used to assay the amount of tryptophan produced in the presence of precursors of tryptophan production (indole and serine) and/or molasses. RESULTS Our results indicate the importance of the Iranian cane molasses not only as carbon source, but also as a source of precursors for tryptophan production. CONCLUSION This report evaluates the potential of cane molasses as an economical source for tryptophan production by B. subtilis, hence eliminating the requirement for additional serine and indole as precursors.