常压室温等离子体诱变高效利用木糖产丁二酸菌株

Mutating Escherichia coli by atmospheric and room temperature plasmas for succinic acid production from xylose

摘要:

大肠杆菌Escherichia coli AFP111是E. coli NZN111 (△pflAB△ldhA) 的ptsG自发突变株，其转化1 mol的木糖合成丁二酸的过程中净产生1.67 mol ATP，但是转化1 mol的木糖合成丁二酸的过程中实际需要2.67 mol ATP，因此在厌氧条件下，ATP的供给不足导致E. coli AFP111不能代谢木糖。采用常压室温等离子体射流诱变产丁二酸大肠杆菌菌株，在厌氧条件下，利用以木糖为碳源的M9培养基，筛选得到一株可以代谢木糖并积累丁二酸的突变株DC111。该突变菌株在发酵培养基中，72 h内可以消耗10.52 g/L木糖产6.46 g/L的丁二酸，丁二酸的得率达到了0.78 mol/mol。而且突变株中伴有ATP产生的磷酸烯醇式丙酮酸羧激酶 (PCK) 途径得到加强，PCK的比酶活相对于出发菌株提高了19.33倍，使得其在厌氧条件下能够有足够的ATP供给来代谢木糖发酵产丁二酸。

Abstract:

Escherichia coli AFP111 is a spontaneous mutant with mutations in the glucose specific phosphotransferase system (ptsG) in NZN111(△pflAB △ldhA). In AFP111, conversion of xylose to succinic acid generates 1.67 molecule of ATP per xylose. However, the strain needs 2.67 molecule ATP for xylose metabolism. Therefore, AFP111 cannot use xylose due to insufficient ATP under anaerobic condition. Through an atmospheric and room temperature plasma (ARTP) jet, we got a mutant strain named DC111 that could use xylose under anaerobic condition in M9 medium to produce succinic acid. After 72 h, DC111 consumed 10.52 g/L xylose to produce 6.46 g/L succinic acid, and the yield was 0.78 mol/mol. Furthermore, the reaction catalyzed by the ATP-generating PEP-carboxykinase (PCK) was enhanced. The specific activity of PCK was 19.33-fold higher in DC111 than that in AFP111, which made the strain have enough ATP to converse xylose to succinic acid.