Enhancement of iminosugar production, 1-deoxynojirimycin and 1-deoxymannojirimycin, in recombinant Corynebacterium glutamicum

The iminosugars 1-deoxynojirimycin (1-DNJ) and 1-deoxymannojirimycin (1-DMJ) were produced by recombinant Corynebacterium glutamicum (CgTYB) bearing the 1-DNJ-producing GabT1-Yktc1-GutB1 (TYB) gene cluster from Bacillus velezensis MBLB0692. The enhanced iminosugar biosynthesis in CgTYB cultures increased both alpha-mannosidase inhibition (AMI) and alpha-glucosidase inhibition (AGI) activity. Individual cultures harboring GabT1, Yktc1, and GutB1 genes were found to be able to produce both 1-DNJ and 1-DMJ in mixed cultures of one pot analysis. This suggests that the genes necessary for epimerization and reduction are intrinsic to the cells rather than close to the 1-DNJ-producing cluster. Glucose was the preferred carbon source and a provision of 10 g/L glucose increased AGI and AMI to 69.8% and 70.1%, respectively. The 1 mM IPTG produced 55.0% AGI and 72.1% AMI, and 20% ethanolic permeabilization produced 62.8% AGI and 74.2% AMI. Batch fermentation increased iminosugar yields from 18.7 to 229.9 mg/L 1-DNJ, and 41.8 to 63.7 mg/mL 1-DMJ.