Study On Glutamic Acid Fermentation Using Corn Stover As Raw Material Through Biorefinery Technology

Glutamic acid is an important commodity chemical and is widely used in different areas such as food, pharmaceuticals. Currently, the market of glutamic acid is expanded gradually. The production of glutamic acid commonly used food-based raw materials such as corn starch. Not only the cost is high, but also it competes with the food and feed supply. Using the cheap and abundant lignocellulose biomass as the raw materials for glutamic production is a promising choice. In this thesis, several different glutamic acid fermenting strains were screened under different concentrations of corn steep liquor (CSL). Corynebacterium glutamicum SIIM B460showed a better fermentability for glutamic acid production in synthetic fermentation medium and in the undetoxicification corn stover hydrolysate. The effect of inhibitors derived from pretreatment operation on cell growth and fermentability of C. glutamicum SIIM B460was investigated. Ten typical inhibitors were selected, including two furan derivatives, three weak acids, and five phenolic compounds. The strain shows a high tolerance to weak acids of acetic acid, formic acid and levulic acid. The fermentation was slightly inhibited by furfural and5-hydroxym ethyl furfural at a relatively high concentration. Syringaldehyde, coniferyl aldehyde, and phenol were found to be the strong inhibitors for C. glutamicum SIIM B460, while4-hydroxybenzaldehyde and vanillin were relatively weak inhibitors. Because corn stover contains excessive biotin for glutamic acid production, the strain is unable to produce glutamic acid without induction. Under the induction of200mg/L penicilin, the strain can produce31g/L glutamic acid using15%solid undetoxcification hydrolysate. The yield is similar to that using glutamic acid fermentation medium. This study provided a preliminary but important method for glutamic acid production from lignocellulose biomass with sound economic competitiveness.