氧化还原电位调控对产琥珀酸放线杆菌代谢通量分布的影响

Effect of redox potential regulation on metabolic flux distribution of succinate production by Actinobacillus succinogenes

利用代谢通量分析方法分析了氧化还原电位调控对产琥珀酸放线杆菌NJ113厌氧发酵产丁二酸过程的影响。结果表明,氧化还原电位调控可以改变HMP与EMP途径的代谢通量,从而影响胞内NADH/NAD+。在菌体最适氧化还原电位(-350 mV)条件下,HMP途径与EMP途径的通量比由43.6∶56.2提高至63.2∶36.5,间接合成更多的NADH,解决了丁二酸合成过程中还原力不足的矛盾,整个发酵过程中胞内NADH/NAD+比值有明显提高,发酵初期NADH/NAD+比值由2.19提高至8.73。最终丁二酸代谢通量从114.5 mmol.(g DCW)-1.h-1增至129.3 mmol.(g DCW)-1.h-1,副产物乙酸、甲酸的代谢通量分别降低30.6%、30.2%;丁二酸收率由75.46%提高至89.34%,生产强度达到1.18 g.L-1.h-1。

The effect of redox potential regulation on metabolite flux distribution of Actinobacillus succinogenes NJ113 was studied by using the metabolic flux analysis method. The results showed that the flux of HMP and EMP were changed after ORP regulation. Under the optimal ORP （-350 mV） condition, the ratio of HMP to EMP was improved from 43.6 ： 56.2 to 63.2 ： 36.5 and thus the reducing power was better balanced. The value of NADH/NAD^＋ at the ORP of -350 mV was much higher than that without regulation. In the initial phase the NADH/NAD^＋ was increased from 2.19 to 8.73. Finally,the succinic acid flux increased from 114.5 mmol · （g DCW）^-1 · h^-1 to 129.3 mmol · （g DCW）^-1 · h^-1with the metabolic flux of acetic acid and formic acid decreased by 30.6% and 30.2%,respectively. Succinic acid yield was increased from 75.46% to 89.34% with the productivity of 1.18 g ·L^-1 · h^-1.