Isolation and Identification of a DNJ Producing Bacterial Strain from Silkworm Faeces and Improvement of Its DNJ Yield Through Mulberry Extracts Induction
In this study, the strain PD04 producing 1-deoxynojirimycin (DNJ) from silkwormfaeces was isolated, and identified as Enterobacter hormaechei by morphology and molecular biology.This strain belongs to acidophilic bacteria with salt tolerance, and the optimal growth temperatureis 40 ℃.The addition of mulberry leaf alkaloids-ethanol extracts, mulberry seed alkaloids-ethanol extracts and mulberry leaf flavonoids-ethanol extracts during the initial fermentation stage of PD04 strain significantly promoted the production of DNJ in the bacterial broth.DNJ productions in the microbial reached the highest points of 17.61 mg/mL, 20.28 mg/mL, and 26.74 mg/mL, respectively, with the addition of 0.10 mg/mL mulberry leaf alkaloids-ethanol extracts, 0.10 mg/mL mulberry seed alkaloids-ethanol extracts, and 0.20 mg/mL mulberry leaf flavonoids-ethanol extracts, respectively.Those DNJ yields were 6.31, 7.27 and 9.45 times of those in the control groups, respectively.The results provide a theoretical basis for the development of microbial DNJ production and application.