earticle

영어

Mannheimia succiniciproducens MBEL55E, a capnophilic rumen bacterium, produces succinic
acid in high concentrations under anaerobic conditions. The cells could not grow below 8.74 mM
of dissolved CO2, indicating that there is a threshold level of CO2 to sustain the growth of M.
succiniciproducens. Succinic acid yield on glucose was 1.49 and 1.52 times higher at 141 mM CO2 than those obtained from 8.74 mM CO2, respectively. Comparing the fermentation results with the levels of key enzyme activities, we found that the efficient carboxylation of phosphoenolpyruvate (PEP) to oxaloacetate, in which CO2-fixation occurs by both PEP carboxykinase (PckA) and PEP carboxylase (Ppc), allows M. succiniciproducens to produce substantial amounts of succinic acid. In particular, the activity of PckA was more than 50 times higher than those of Ppc and malic enzyme (SfcA). The results provide useful information for the design of effective bioprocesses by maximizing CO2 availability and also for the rational metabolic engineering by optimizing metabolic fluxes to improve succinic acid production[This work was supported by the Genomebased Integrated Bioprocess Project of the Ministry of Education, Science and Technology (MEST, No. 2005-01294) through the Korea Science and Engineering Foundation (KOSEF). Further supports by the LG Chem Chair Professorship, WCU(World Class University) program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology (MEST, R32-2008-000-10142-0), and by the KOSEF through the Center for Ultramicrochemical Process Systems are appreciated.]