| Affiliation: | 1. Genetics of Prokaryotes, Faculty of Biology & CeBiTec, Bielefeld University, Universitätsstr. 25, 33615 Bielefeld, Germany;2. Genetics of Prokaryotes, Faculty of Biology & CeBiTec, Bielefeld University, Universitätsstr. 25, 33615 Bielefeld, Germany These authors contributed equally to this work.;3. Multiscale Bioengineering, Technical Faculty and CeBiTec, Bielefeld University, Universitätsstr. 25, 33615 Bielefeld, Germany;4. Department of Food Science & Biotechnology, Kyungsung University, 309, Suyeong-ro, Nam-gu, Busan, 48434 Republic of Korea |
| Abstract: | The aromatic amino acid l -tryptophan serves as a precursor for many valuable compounds such as neuromodulators, indoleamines and indole alkaloids. In this work, tryptophan biosynthesis was extended by halogenation followed by decarboxylation to the respective tryptamines or cleavage to the respective indoles. Either the tryptophanase genes tnaAs from E. coli and Proteus vulgaris or the aromatic amino acid decarboxylase genes AADCs from Bacillus atrophaeus, Clostridium sporogenes, and Ruminococcus gnavus were expressed in Corynebacterium glutamicum strains producing (halogenated) tryptophan. Regarding indoles, final titers of 16 mg L−1 7-Cl-indole and 23 mg L−1 7-Br-indole were attained. Tryptamine production led to a much higher titer of 2.26 g L−1 upon expression of AADC from B. atrophaeus. AADC enzymes were shown to be active with halogenated tryptophan in vitro and in vivo and supported production of 0.36 g L−1 7-Br-tryptamine with a volumetric productivity of 8.3 mg L−1 h−1 in a fed-batch fermentation. |
