1-Deoxynojirimycin (DNJ), a potent α-glycosidase inhibitor, has therapeutic applications in treatments of HIV, Gaucher's disease, and diabetes. DNJ has been extracted from natural sources (mulberry leaves) for therapeutic purposes; however, DNJ ingredients are in limited supply and are costly to obtain on a large scale. Since certain strains of Bacillus and Streptomyces species reportedly produce DNJ, they may serve as potential sources for high-yield DNJ production. In this study, we obtained evidence for a DNJ production in Bacillus subtilis DSM704 by hydrophilic interaction chromatography-tandem mass spectrometry. In addition, from a screen of 750 microorganisms, we identified additional Bacillus strains (Bacillus amyloliquefaciens AS385 and Bacillus subtilis B4) that produce DNJ in large quantities. Investigation of the effect of various culture conditions, using Bacillus subtilis DSM704 and the DNJ high-production Bacillus strains, provided evidence for the importance of sorbitol supplementation on the yield of the DNJ precursor, 2-amino-2-deoxy-D-mannitol, thereby increasing DNJ production. The role of sorbitol in increased DNJ production was supported by an observed increase in mRNA expression of the biosynthetic gene, gabT1. When Bacillus amyloliquefaciens AS385 was cultured in medium supplemented with sorbitol, extracellular DNJ concentration reached a maximum of 460 mg/l of medium (equivalent to 9.20mg/g of freeze-dried medium), indicating that this strain can serve as a source for food- and drug-grade products. These findings not only lead to a further understanding of the DNJ biosynthetic pathway, but also suggest a method for microbial mass production of DNJ for therapeutic applications.
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