系统代谢工程改造树干毕赤酵母生产琥珀酸

为提高树干毕赤酵母发酵生产琥珀酸的产量,借助基因组规模代谢网络模型iTL885获得琥珀酸合成的最佳代谢途径为扩增icl1基因和敲除sdh1基因。在此基础上,借助代谢工程策略构建过量表达异柠檬酸裂解酶基因icl1的重组菌株FPLicl、缺失琥珀酸脱氢酶基因sdh1的重组菌株FPLΔsdh和缺失sdh1基因同时过量表达icl1基因的重组菌株FPLΔsdh-icl。结果表明:3株重组菌的异柠檬酸裂解酶活性由0.33 U/mg分别增加为1.6、5.6和6.6U/mg;而琥珀酸脱氢酶活性则从13.8 U/mg分别降为10.7、0.3和0.3 U/mg。在以木糖为C源的培养基中,3株重组菌生产琥珀酸的能力分别是0.30、1.20和1.60 g/L。

System metabolic engineering of Pichia stipitis for succinic acid production

To improve the succinic acid production by Pichia stipites with xylose as sole carbon source,an optimum synthesis pathway for succinate production in P. stipites was obtained through aiding by genome-scale metabolic model iTL885.In this optimum pathway,isocitrate lyase gene icl1 was overexpressed but succinate dehydrogenase gene sdh1 should be deleted.Then, the genetic engineering stains FPLicl over-expressing icl1,FPLΔsdh deleting sdh1 and FPLΔsdh-icl with sdh1-deleted and icl1 over-expressed were constructed.The ICL enzyme activity reached at 1.6, 5.6 and 6.6 U/mg, the SDH enzyme activity reduced to 10.7,0.3 and 0.3 U/mg in the three strains,respectively.As a result,0.30,1.20 and 1.60 g/L succinate were produced by the three engineered strains on xylose as carbon source.