Improvement of 1-deoxynojirimycin production of Bacillus amyloliquefaciens by gene overexpression and medium optimization

Although 1-deoxynojirimycin (DNJ) is an efficient α-glucosidase inhibitor, its lower yield limited its application. In this study, the integration of DNJ synthase genes gabT1, yktC1, and gutB1 into Bacillus amyloliquefaciens HZ-12 genome promoted DNJ production, resulting in 19.11%, 13.40%, and 16.70% increase in DNJ yield, respectively. Furthermore, the strain of B. amyloliquefaciens HZ-12/TB integrated with gabT1 and gutB1 was more conducive to improve DNJ production than the strain simultaneously integrated with gabT1, yktC1, and gutB1. Overexpression of glcP not only promoted the synthesis of DNJ efficiently, but also reduced the production of by-product acetoin. Then, the strain of B. amyloliquefaciens HZ-12/TBP integrated with gabT1, gutB1, and glcP was resulted in 32.52% increase in DNJ production compared with B. amyloliquefaciens HZ-12. In addition, 20 g/kg lactose and 10 g/kg malt extract added into soybean solid medium were more beneficial for DNJ yield (1135.60 mg/kg). This study demonstrated that enhancing the synthesis pathway and glucose transport, and optimization of medium effectively improved the yield of DNJ in B. amyloliquefaciens, respectively, which provide an effective method to produce high level of DNJ.