Metabolic engineering of Mannheimia succiniciproducens for the homo succinic acid production

Abstract

Using proteome analysis and carbon source diversification strategy, high performance Mannheimia succiniciproducens strains producing succinic acid have been developed through this study. Monitoring cellular and metabolic status by proteome analysis in several different conditions offered many clues to improve succinic acid production. The proteome information gives directions for further enhancement in succinic acid production in the aspect of productivity and yield. Hence, sucrose has been used to achieve succinic acid production with reduced pyruvate formation. However, the discrepancy between the fermentation result and the deduced hypothesis from genome sequence leaded to identify sucrose utilization system in detail in M. succiniciproducens. Based on the identification information, productivity-enhanced strain was developed aided with adaptive evolution. Cellular and metabolic status was also examined by using proteome analysis and its property was finally confirmed by using a fed-batch fermentation and molasses simulation liquid. In addition, to redesign the high yield succinic acid producing strain, genetic modification has been carried out with carbon source diversification strategy. Finally, high yield and high productive complete homo succinic acid producing M. succiniciproducens in sucrose and glycerol medium as dual carbon sources has been constructed for the first time. Analyzing its proteome and considering the identified sucrose utilization system, it can be understood how the sucrose and glycerol can be used simultaneously by overcoming the catabolite repression mechanism.