Lactose Increases the Production of 1-deoxynojirimycin in Bacillus amyloliquefaciens

1-Deoxynojirimycin (DNJ) is an effective sugar analogue that suppresses the elevation of postprandial blood glucose. Therefore, food products containing DNJ are expected to be promising functional foods in preventing the onset of diabetes. To examine the absorption kinetics of DNJ, we prepared N-15-labeled DNJ from the culture medium of a Bacillus amyloliquefaciens DSM7 strain. In the process, we found that lactose markedly increased the production of DNJ at a carbon/nitrogen ratio of 6.25:1, reaching 1140 mg/L with 5 days of cultivation. Comparisons between lactose and glucose on cell growth and DNJ production suggested that lactose made the DSM7 strain grow more slowly and maintained DNJ production in the long term. These findings may be useful for efficient microbial DNJ production or in the development of DNJ-containing fermented food products.