Screening and Optimization of High-Yield Diastase-Producing Strains from Shedian Baijiu Fermented Mash

摘要

Diastase-producing bacteria were isolated from the fermented mash of Shedian baijiu (stilled liquors). Then the bacteria were preliminarily screened with a transparent ring method and diastatic activity was detected for secondary screening. Finally, 1 high-yield diastase-producing strain was obtained and identified as Bacillus velezensis by morphologic observation and 16S rDNA molecular biological identification. The enzyme-producing conditions of this strain were studied via single-factor experiments and optimized through response surface method. On basis of liquid fermentation medium, the optimal diastasic conditions of this strain were: soluble starch as the carbon source, peptone as the nitrogen source, initial pH 4.0, inoculation amount of 10%, and fermentation time of 3 d. The enzymatic activity after optimization was up to 120.87 ± 1.37 U/mL, or 4.06 times the initial activity.