Scale-up study on fermentative succinic acid production from wheat straw following a cascading biorefinery approach

Succinic acid, as a valuable building block for the food, pharmaceutical and chemical industry, was produced in this study from lignocellulosic biomass by fermentation, employing Actinobacillus succinogenes 130Z. After separation of lignin from wheat straw by the German SME LXP Group GmbH, residual LX-Cellulose was used for enzymatic hydrolysis and fermentation studies, transferring results from lab to pilot scale. Reduction of 73–52 % saccharification yield was noted for lab compared to pilot hydrolysis, highlighting the risk of contamination and challenge of sterilization in larger vessels. After decantation, 170 L of clarified hydrolysate were gained. Separate hydrolysis and direct fermentation resulted in the highest SA titer of 28 g·L −1 in lab scale. However at maximum SA yield of 72 %, highest productivity was noted for work with clarified hydrolysate, reaching 0.8 g·L −1 ·h −1 . Carbon provision was compared, providing Na 2 CO 3 or CO 2 as co-substrate to the fermentation. Following the Na 2 CO 3 method, results were successfully reproduced in pilot scale of 50 L, reaching 20 g·L −1 succinic acid at 73 % yield and 0.8 g·L −1 ·h −1 productivity. At complete glucose and xylose conversion, the by-product ratio was 32 %. Substitution of tryptic soy broth with hydrolysate for preculture preparation was found to be feasible, resulting in comparable results. By assessing prospects and key limitations along process scale-up, valuable information is gained to improve the design of SA production from lignocellulosic biomass, when striving for a robust industrial application. • Scale-up of enzymatic hydrolysis and decantation yielded 170 L of hydrolysate. • While advantageous for fermentation, lack of inhibitors raised contamination risk. • Fermentation of hydrolysate with solids resulted in 28 g·L −1 of succinic acid. • Fermentation of clarified hydrolysate was successfully reproduced in 50 L pilot scale. • Cost reduction was demonstrated by substituting TSB- with hydrolysate preculture.