【摘要】 大肠杆菌(E.coli) RRl质粒(pGTE5)的β-内酰胺酶基因(β-lactamase gene)可以在E.coli与枯草杆菌(Bacillus subtilis)中复制和表达。但是,在E.coli细胞中向胞外分泌β-内酰胺酶量少,活力低,对氨苄青霉素(Ampicillin,简称Ap)的抗性也低。将该菌株用紫外线(30w,40cm,150s)和硫酸二乙酯双重诱变,在含Ap的LB平板上筛选到E.coli质粒突变体(p~# GTE5)。对质粒突变体(p~# GTE5)的β-内酰胺酶胞外酶活性进行分析表明,质粒突变体(p~# GTE5)的β-内酰胺酶基因的胞外酶含量、活力及对Ap的抗性增加约10倍。质粒突变体的DNA能在枯草杆菌原生质球中转化,而且β-内酰胺酶基因也能在转化细胞中表达,质粒突变体(p~# GTE5)仍然保持穿梭质粒的特性。更多还原

【Abstract】 β-lactamase gene of E. coli RRI plasmid(pGTE5) could express in Both E. coli andBacillus subtilts, but the extracellular β-lacta-mase activity and resistance to Ampicillin inE. coli is very low. For increasing β-lacta-mase activity of plasmid (pGTE5), the E. coliRRI (pGTE5) strain was induced by botbUV (30 w, 40 cm, 150s) and diethyl sulfate.A plasmid mutant (p~# GTE5) was selectedby increasing it’s resistance to Ampicillin(Ap). Cells of E. coli with plasmid mutant(p~# GTE5) which cloned the β-lactamasegene of Bacillus licheniformis were able tosecret a large amount of protein into the eul-ture broth. The extracellular β-lactamase ac-tivity and resistance to Ampicillin is aboutten times higher than cells containing normalplasmid (p~# GTE5). The β-lactamase genecould express after transformation of(p~# GTE5) DNA into spheroplast of Bacillussubtilis. The plasmid mutant (p~# GTE5)remains the character of shuttle plasmid.更多还原