摘要
以插入AOX1启动子调控S-腺苷甲硫氨酸(SAM)合成酶/VHb表达单元的重组毕赤酵母为对象,研究了甲醇浓度及vgb表达对菌体生长、SAM产量及SAM合成酶活力的影响,同时也考察了vgb表达对胞内ATP含量及细胞活性的影响。结果表明:甲醇浓度(φ(CH3OH))由0.008提高至0.016后,可提高菌体浓度、SAM产量及单位菌体SAM含量;当φ(CH3OH)=0.024时,SAM产量及单位菌体SAM含量与φ(CH3OH)=0.016时相当,而菌体浓度稍低于φ(CH3OH)=0.016时,高于φ(CH3OH)=0.008时的菌体浓度。提高甲醇浓度导致SAM合成酶活力降低,细胞死亡率增加,说明在所考察的重组菌中SAM合成酶的活性并不是SAM合成的限制因素。在上述3种甲醇浓度时,透明颤菌血红蛋白VHb表达都改善了细胞活性,并在较高甲醇浓度(0.016和0.024)时提高了胞内ATP含量。
Effects of methanol concentration on S-adenosyl-L-methionine （SAM） production, cell growth, and SAM synthetase activity（SAMs） were studied in recombinant pichia pastoris strains containing SAMs and Vitreoscilla hemoglobin （VHb） expression cassettes driven by the AOX1 promoter. Impacts of VHb expression on ATP content and cell viability were also studied. Results indicated that the increase of methanol concentration（g） from 0. 008 to 0.016 obviously increased cell density, SAM productivity and specific yield of SAM. When φ（CH3OH）=0. 024, SAM productivity and specific yield of SAM were comparable to that of φ（CH3OH）=0. 016, whereas cell density was slightly lower than that of 0. 016 but higher than that of φ（CH3OH）=0.008. Meanwhile, the increase of methanol concentration resulted in reduced SAM synthetase activity and cell viability, suggesting that SAM synthetase activity was not the limiting factor for SAM synthesis in these recombinant strains. In all methanol concentrations tested, expression of VHb improved cell viability. ATP content was enhanced in the higher methanol concentration of 0. 016 and 0.024 in VHb＋ recombinant cells.
出处
《华东理工大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2008年第3期354-359,共6页
Journal of East China University of Science and Technology
基金
华东理工大学优秀青年教师科研基金
上海市曙光跟踪计划资助项目(06GG07)
上海市浦江人才计划(07pj14027)
