α-淀粉酶产生菌的分离筛选与诱变选育

Separation and Mutagenesis of Alpha-amylase Producing Bacillus

从土样、水样和面样中分离产α-粉酶的芽胞杆菌，对3个样品进行淀粉平板分离和革兰氏染色、芽胞染色，选出产α-淀粉酶芽胞杆菌10株（土样4株、面样3株、水样3株），同时测得其水解圈直径与菌落直径的比值，均在1．9～2．6之间，通过产淀粉酶液体培养基发酵产酶，采用比色法测定发酵液中α-淀粉酶活力均在4．8-5．7g／mL之间。以筛选出产酶活力较高的菌株为出发菌株，进行紫外线诱变选育，经过大量筛选得到优良菌株，在适宜条件下经过发酵其仪一淀粉酶活力可达9．6-13．0g／mL，较出发菌株酶活力提高了69．9％-129．5％。

Ten alpha-amylase producing Bacillus strains were isolated from soil （four strains）, water （three strains） and flour （three strains） through isolation with starch plates, Gram＇s staining and spore staining. The ratio of hydrolysis zone diameter to colony diameter was 1.9-2.6. Liquid culture medium was used for fermentation to produce amylase. The activity of alpha-amylase was determined by colorimetry, and it was 4.8-5.7 g/mL in fermentation broth. The original strains producing high-activity alpha-amylase was selected and mutated by UV mutagenesis. Excellent strains were obtained, and their activity of alpha-amylase was up to 9.6-13.0 g/mL under suitable conditions, which was 69.9%-129.5% higher than that before selection.