The recombinant plasmid pMExfdhDE constructed in Example 2 was transformed into Mannheimia succiniciproducens MBEL55E by electroporation to prepare MBEL55EpMExfdhDE. Also, pMEx was introduced into Mannheimia succiniciproducens MBEL55E, to prepare MBEL55EpMEx.

Each of the prepared recombinant strains was inoculated in 10 ml of a complex medium containing 9 g/l of glucose and cultured in an anaerobic condition at 39° C. for 16 hours. Each of the cultured strains was transferred in 250 ml of a complex medium containing 9 g/l of glucose and further cultured in the medium at 39° C. At this time, 100 μg/l of ampicillin as an antibiotic was added. The fermentation of each of the strains was performed by inoculating 250 ml of the Mannheimia culture broth in 2.5 L of a complex medium, and the fermentation conditions were as follows: initial glucose concentration: 20 g/l, pH: 6.8, and culture temperature: 39° C. For the adjustment of pH during the fermentation, ammonia solution (28%, v/v) was used, and the concentration of antibiotic ampicillin was the same as described above. A sample from each of the recombinant Mannheimia strains was collected during the fermentation, and the collected sample was centrifuged at 13,000 rpm and 4° C. for 10 minutes, and the concentrations of metabolites and succinic acid(cas:110-15-6) in the supernatant were analyzed by high-performance liquid chromatography (HPLC). The results are shown in Table 3 below.