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.