摘要
用2升全自动发酵罐观察大肠杆菌工程菌Ec108(pPAHD1)青霉素酰化酶(Penicillin-G-acylase)基因的表达,发现溶解氧浓度对生物量的扩增和基因产物的积累有显著的影响。对数前期扩增生物量时需要相对高的溶解氧,以不低于相对饱和度80％为宜;而产酶阶段则要求相对低的溶解氧环境,可保持相对饱和度5％。按溶解氧峰形变化特征,指导补加苯乙酸的时机;以尖峰出现的间距,决定补加剂量,采用每次补加0.03～0.05％为佳。在罐压0.3kg/cm2,通气比1:0.5及恒温条件下,借助上述手段,最高酶活水平已达342u/100ml(NIPAB法),比摇瓶发酵酶活提高1.8倍。
The conditions for expression of penicillin-G-acylase gene using hybrid strain E. coli 108(pPAHD1)were studied in 2-liter automatic fermenter. The growth of the strain and the expression of the penicillin-G-acylase gene were influenced obviously by the dissolved oxygen level in the medium. Experiments revealed that a high dissolved oxygen level no less than 80% saturation was demanded for accumulation of biomass in early log growth phase and it shifted down to 5 % saturation to be compulsory for superproduction of the enzyme. Signals of variable dissolved oxygen peaks were found of great significance for phenylacetic acid addition. The quantities of phenylacetic acid added were correlated with the peak intervals and the proper dosage used in each addition would bring the concentration to 0.03-0.05%. Under the circumstances of 0.3 kg/cm pressure, 1:0.5v/v/m air flow, defined temperature and other controlled conditions, the level of penicillin-G-acylase activity has been reached 342U/100ml(NIPAB method), which is 1.8 fold higher in comparison with the shaking flask fermentation.
出处
《中国抗生素杂志》
CAS
CSCD
北大核心
1991年第4期251-255,共5页
Chinese Journal of Antibiotics
关键词
青霉素酰化酶
溶解氧
诱导剂
Penicillin acylase
Dissolved uxygen
Inducor
