CAJ | 학술논문

为有效降低L-苏氨酸发酵过程中副产物的积累,考察了发酵过程中的溶氧强制振荡对L-苏氨酸发酵产率及其多种副产物积累的影响,并深入探讨了振荡行为对L-苏氨酸生物合成代谢网络的代谢流分布的影响.结果表明:采用溶氧强制振荡工艺能够明显提高L-苏氨酸的发酵产率和降低多种抑制性产物的合成.与非振荡工艺相比,经过36 h培养,细胞生物量达到29.5 g·L~(-1),苏氨酸的质量浓度达到118.9 g·L~(-1),而乙酸质量浓度下降到0.8 g·L~(-1),副产的其他氨基酸也大大降低. 通过代谢流分析表明,在发酵后期的一个振荡周期(30 h至 31 h)内,与非振荡组相比,HMP途径的代谢流量由6.5提高至95.88,CO2固定反应代谢流量由45.1提高至86.1,TCA循环相对代谢流量从1.86提高至17.78,从而导致苏氨酸对葡萄糖的质量转化率从30.0 % 增加至57.0%.溶氧强制振荡条件下的苏氨酸发酵液中各种副产物更少,更适合今后的大规模工业化生产.
위유효강저L-소안산발효과정중부산물적적루,고찰료발효과정중적용양강제진탕대L-소안산발효산솔급기다충부산물적루적영향,병심입탐토료진탕행위대L-소안산생물합성대사망락적대사류분포적영향.결과표명:채용용양강제진탕공예능구명현제고L-소안산적발효산솔화강저다충억제성산물적합성.여비진탕공예상비,경과36 h배양,세포생물량체도29.5 g·L~(-1),소안산적질량농도체도118.9 g·L~(-1),이을산질량농도하강도0.8 g·L~(-1),부산적기타안기산야대대강저. 통과대사류분석표명,재발효후기적일개진탕주기(30 h지 31 h)내,여비진탕조상비,HMP도경적대사류량유6.5제고지95.88,CO2고정반응대사류량유45.1제고지86.1,TCA순배상대대사류량종1.86제고지17.78,종이도치소안산대포도당적질량전화솔종30.0 % 증가지57.0%.용양강제진탕조건하적소안산발효액중각충부산물경소,경괄합금후적대규모공업화생산.
In order to reduce the accumulation of byproducts significantly, the dissolved oxygen (DO) forced oscillation was designed and evaluated for enhancing biosynthesis of L-threonine with recombinant E.coli TRFC. The results show that this new DO control mode could improve the productivity of L-threonine and reduce the accumulation of the byproducts greatly. With this DO oscillation mode, the cell density and L-threonine concentration are improved up to 29.5 g·L~(-1) and 118.9 g·L~(-1), respectively; whereas, the acetate concentration is reduced to 0.8 g·L~(-1). Further analysis of metabolic flux distribution shows that, compared with the non-DO control mode, the carbon flux to HMP (Hexose Monophosphate Pathway) is increased from 6.5 to 95.88, the anaplerotic reaction from 45.1 to 86.1 and the TCA(Tricar boxylic acid) cycle relative flux from 1.86 to 17.78 during the oscillation period from 30 h to 31 h. The shift of these metabolic fluxes leads to the obvious increase of the glucose-to-L-threonine conversion ratio from 30.0% to 57.0%. Further analyses of both DO controlled and non-controlled fermentation broths show that the concentrations of different byproducts are greatly reduced with the dissolved oxygen forced oscillation. The present work is very helpful to improve the commercial production of L-threonine in the future.