L-天冬酰胺酶工程菌株培养条件及稳定性

CULTURE CONDITIONS OF ENGINEERED STRAIN OF L\|ASPARAGINASE AND THE RECOMBINANT PLASMID STABILITY

Ｌ天冬酰胺酶工程菌株的酶活和表达水平受菌体生物量和诱导时间的影响。在生物量Ａ６０００３ ×１０ 左右，热诱导４ｈ 酶活力和表达水平可达到较高水平。葡萄糖对酶的生成有阻遏作用，当葡萄糖浓度大于０２５ ％ 时，对工程菌酶的合成造成阻遏。确定了工程菌培养的培养基、ｐＨ 值、接种量等因素。重组质粒ｐＡＳＮ 在Ｅ．ｃｏｌｉＪＭ１０５ ，ＴＧ１ 和ＡＳ１３５７ 等宿主菌中具有很好的稳定性，工程菌培养５０ 代以上重组质粒保留９０ ％ 以上，在ＬＢ 和Ｍ３

The growth curves of engineered strain JM105(pASN) were different in LB and M\|3 media. The expression level and activity of L\|asparaginase were affected apparently by both biomass and induction time. Glucose repression of production of L\|asparaginase was found. The stability of the recombinant plasmid pASN in different host strains and in LB and M\|3 media was determined. After cultivation inLB broth and M\|3 media at 30℃ for more than 50 generations without antibiotic selection, then induced at 42℃ for up to 5h, the engineered strains were proved to be stable, except for DH5α(pASN).