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BACKGROUND Succinic acid is one of the most important biorefinery platform chemicals. The fibrous‐bed bioreactor (FBB), comprising spiral cotton fiber packed in a modified bioreactor, is effective for anaerobic cell‐immobilized fermentation. In this study, fermentation production of succinic acid by Actinobacillus succinogenes using a FBB was investigated. RESULTS The effect of different initial glucose concentrations on succinic acid production in batch fermentation in a FBB was examined, which indicated that the optimal initial glucose concentration was 55 g L‐1. In 10 batches of repeated‐batch fermentation, the average succinic acid productivity, concentration, and yield were 3.61 g L‐1 h‐1, 39.0 g L‐1, and 0.85 g g‐1, respectively. A maximum succinic acid concentration of 98.7 g L‐1 was reached in fed‐batch fermentation comprising four batches of fermentation, with a succinic acid yield of 0.89 g g‐1 and productivity of 2.77 g L‐1 h‐1. CONCLUSION Succinic acid fermentation by A. succinogenes in a FBB was successfully performed to enhance succinic acid productivity. And also, high succinic acid concentration with high reactor productivity and yield were simultaneously achieved in the FBB with fed‐batch fermentation. © 2013 Society of Chemical Industry

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Boronic acids have become one of the most prevalent classes of reagents in modern organic synthesis, displaying various reactivity profile via C-B bond cleavage. Herein, we describe the utilization of...

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Succinic acid is an important platform chemical for synthesis of C4 compounds. We applied genome shuffling to improve fermentative production of succinic acid by A. succinogenes. Using a screening strategy composed of selection in fermentation broth, cultured in 96-deep-well plates, and condensed HPLC screening, a starting population of 11 mutants producing a higher succinic acid concentration was selected and subjected to recursive protoplasts fusion. After three rounds of genome shuffling, strain F3-II-3-F was obtained, producing succinic acid at 1.99 g/l/h with a yield of 95.6 g/l. The genome shuffled strain had about a 73 % improvement in succinic acid production compared to the parent strain after 48 h in fed-batch fermentation. The genomic variability of F3-II-3-F was confirmed by amplified fragment-length polymorphism. The activity levels of key enzymes involved in end-product formation from glucose and metabolic flux distribution during succinic acid production were compared between A. succinogenes CGMCC 1593 and F3-II-3-F. Increased activity of glucokinase, fructose-1,6-bisphosphate aldolase, PEP carboxykinase and fumarase, as well as decreased activity of pyruvate kinase, pyruvate formate-lyase, and acetate kinase explained the enhanced succinic acid production and decreased acetic acid formation. Metabolic flux analysis suggested that increased flux to NADH was the main reason for increased activity of the C4 pathway resulting in increased yields of succinic acid. The present work will be propitious to the development of a bio-succinic acid fermentation industry.

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