초록
<P><B>Abstract</B></P> <P>The aim of the present study is to develop an effective bioprocess for converting CO<SUB>2</SUB> into succinic acid (SA) with <I>Actinobacillus succinogenes</I> by an integrated fermentation and membrane separation process. CO<SUB>2</SUB> could be effectively converted into SA using NaOH as the neutralizer under the completely closed exhaust pipe case with self-circulation of CO<SUB>2</SUB> in the bioreactor. Meanwhile, the optimal CO<SUB>2</SUB> partial pressure was 0.4 bar. In addition, a 300 kDa ultrafiltration (UF) membrane was preferred for constructing the membrane bioreactor. Moreover, a high conductivity was toxic to the cells during SA biosynthesis. After removing the high concentration salts by <I>in-situ</I> membrane filtration, the SA productivity and CO<SUB>2</SUB> fixation rate increased by 39.2% compared with the batch culture, reaching 1.39 g·L<SUP>−1</SUP>·h<SUP>−1</SUP> and 0.52 g·L<SUP>−1</SUP>·h<SUP>−1</SUP> respectively. Furthermore, nanofiltration (NF) was suitable for purifying the SA and recovering the residual substrates in the UF permeate for the next fermentation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CO<SUB>2</SUB> was effectively converted into SA by fermentation under mild pressure. </LI> <LI> CO<SUB>2</SUB> could be fully used under mid-pressure with self-circulation in the bioreactor. </LI> <LI> SA productivity was enhanced by an integrated bioprocess. </LI> <LI> NF was successfully used for the decoloration and recovery of SA. </LI> <LI> NF retentate was recycled for the fermentation. </LI> </UL> </P>