Fig. 1

Linking the metabolism of L. lactis and L. brevis to achieve 2-butanol production. a Metabolic pathway based on L. lactis CS4363 (mBDO added in the medium). The constructed strain encodes: PddABC, diol dehydratase, and DdrAB, reactivase from K. oxytoca; SadB, secondary alcohol dehydrogenase from A. xylosoxidans. Pathways in gray indicate activities that have been eliminated. Dashed lines indicate multiple enzymatic steps. b The combined metabolic pathway for L. lactis and L. brevis. Bdh, butanediol dehydrogenase from Enterobacter cloacae. DDH, diol dehydratase; DDHr, diol dehydratase reactivate; SAD, secondary alcohol dehydrogenase. Only heterologously expressed gene activities in L. lactis and activities related to 2-butanol synthesis in L. brevis are highlighted