Characterization of a flavin-containing monooxygenase from Corynebacterium glutamicum and its application to production of indigo and indirubin

Abstract

Objective: To examine the role of a gene encoding flavin-containing monooxygenase (cFMO) from Corynebacterium glutamicum ATCC13032 when cloned and expressed in Escherichia coli for the production of indigo pigments.

Results: The blue pigments produced by recombinant E. coli were identified as indigo and indirubin. The cFMO was purified as a fused form with maltose-binding protein (MBP). The enzyme was optimal at 25 °C and pH 8. From absorption spectrum analysis, the cFMO was classified as a flavoprotein. FMO activity was strongly inhibited by 1 mM Cu(2+) and recovered by adding 1-10 mM EDTA. The enzyme catalyzed the oxidation of TMA, thiourea, and cysteamine, but not glutathione or cysteine. MBP-cFMO had an indole oxygenase activity through oxygenation of indole to indoxyl. The recombinant E. coli produced 685 mg indigo l(-1) and 103 mg indirubin l(-1) from 2.5 g L-tryptophan l(-1).

Conclusion: The results suggest the cFMO can be used for the microbial production of both indigo and indirubin.