First, the strain, was treated by NTG, DES, then the methionine induction model and methylamine tolerance model were used as screening models to select strains, as a result, a favorable strain DMa-46 was obtained, its B1a components was about 43.2%.

• 首先采用了亚硝基胍和硫酸二乙酯进行诱变处理，处理后采用了甲硫氨酸诱导模型和甲胺耐受的模型，对菌株进行了选育，获得了有效组分Bla高达43.；2%25的菌株-DMa-46。