1-deoxynojirimycin (1-DNJ), a potent a-glycosidase inhibitor, has therapeutic applications in treatments of HIV, Gaucher’s disease, and diabetes. 1-DNJ has been extracted from natural sources (mulberry leaves) for therapeutic purposes; however, 1-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 1-DNJ, they may serve as potential sources for high-yield 1-DNJ production. In this study, we obtained evidence for four bacteria that produce 1-DNJ in large quantities by high performance liquid chromatography and thin layer chromatography. Investigation of the effect of mulberry leaves powder concentration(1~5%), using the 1-DNJ high-production bacteria, provided evidence for microbial mass production of 1-DNJ.