Enhanced 1-deoxynojirimycin production in Bacillus amyloliquefaciens TU11 strain via random mutagenesis and statistical optimization

Abstract

1-Deoxynojirimycin (DNJ) is a polyhydroxylated alkaloid with α-glucosidase inhibitory (AGI) activity, possessing potential as an anti-diabetes and anti-virus agent. In this study, Bacillus amyloliquefaciens TU11 showing AGI activity was isolated from a Vietnamese traditional soybean-fermented food, and its DNJ production was confirmed. The B. amyloliquefaciens TUN.327 mutant strain, which exhibits increased DNJ production, was obtained by subjecting the B. amyloliquefaciens TU11 strain to random mutagenesis using UV irradiation and N-methyl-N′-nitro-N-nitrosoguanidin treatment. To further enhance DNJ production, the effects of nine culture parameters and physical conditions were evaluated using the Plackett？Burman design. The results suggested that inoculum size, temperature, and FeSO4.7H2O were the most influential factors affecting DNJ production. Finally, the optimal culture conditions for maximizing DNJ concentration by B. amyloliquefaciens TUN.327 were predicted using Box？Behnken designs. Under the optimal culture conditions, B. amyloliquefaciens TUN.327 achieved a DNJ production of 2,167？±？350 mg/L, which represents a ninefold increase compared to the wild-type TU11 cultured in the unoptimized medium (233？±？30 mg/L).