title: Effects of dissolved CO2 levels on the growth of Mannheimia succiniciproducens and succinic acid production.
abstract: A capnophilic rumen bacterium Mannheimia succiniciproducens produces succinic acid as a major fermentation end product under CO(2)-rich anaerobic condition. Since succinic acid is produced by carboxylation of C3 compounds during the fermentation, intracellular CO(2) availability is important for efficient succinic acid formation. Here, we investigated the metabolic responses of M. succiniciproducens to the different dissolved CO(2) concentrations (0-260 mM). Cell growth was severely suppressed when the dissolved CO(2) concentration was below 8.74 mM. On the other hand, cell growth and succinic acid production increased proportionally as the dissolved CO(2) concentration increased from 8.74 to 141 mM. The yields of biomass and succinic acid on glucose obtained at the dissolved CO(2) concentration of 141 mM were 1.49 and 1.52 times higher, respectively, than those obtained at the dissolved CO(2) concentration of 8.74 mM. It was also found that the additional CO(2) source provided in the form of NaHCO(3), MgCO(3), or CaCO(3) had positive effects on cell growth and succinic acid production. However, growth inhibition was observed when excessive bicarbonate salts were added. By the comparison of the activities of key enzymes, it was found that PEP carboxylation by PEP carboxykinase (PckA) is the most important for succinic acid production as well as the growth of M. succiniciproducens by providing additional ATP.
authors.affiliation: Department of Chemical and Biomolecular Engineering (BK21 Program) and BioProcess Engineering Research Center, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701, Republic of Korea.
authors.forename: Hyohak
authors.initials: H
authors.lastname: Song
authors.forename: Jeong Wook
authors.initials: JW
authors.lastname: Lee
authors.forename: Sol
authors.initials: S
authors.lastname: Choi
authors.forename: Jong Kyun
authors.initials: JK
authors.lastname: You
authors.forename: Won Hi
authors.initials: WH
authors.lastname: Hong
authors.forename: Sang Yup
authors.initials: SY
authors.lastname: Lee
mesh_terms: D000693:Anaerobiosis; D002119:Calcium Carbonate / Q000494:pharmacology; D002245:Carbon Dioxide / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D005285:Fermentation; D008274:Magnesium / Q000494:pharmacology; D031121:Mannheimia / Q000187:drug effects* / Q000254:growth & development* / Q000378:metabolism; D008954:Models, Biological; D019764:Phosphoenolpyruvate Carboxykinase (ATP) / Q000187:drug effects / Q000378:metabolism; D011312:Pressure; D019289:Pyruvic Acid / Q000378:metabolism; D017693:Sodium Bicarbonate / Q000494:pharmacology; D019802:Succinic Acid / Q000032:analysis / Q000378:metabolism*
chemical_list: C005479:magnesium carbonate; D002245:Carbon Dioxide; D019289:Pyruvic Acid; D017693:Sodium Bicarbonate; D019802:Succinic Acid; D019764:Phosphoenolpyruvate Carboxykinase (ATP); D002119:Calcium Carbonate; D008274:Magnesium