High production yield and specific productivity of succinate from cassava starch by metabolically-engineered Escherichia coli KJ122

Abstract

BACKGROUND: Succinate has been widely used in chemical industries and its microbial production is a desirable option. The feasibility of bio-based succinate production on an industrial scale strongly depends on the utilization of cheaper renewable resources. The use of cassava starch may make the fermentation process of succinate more economically competitive. RESULTS: Simultaneous saccharification and fermentation (SSF) of succinate production was performed in minimal salt medium containing a cheap cassava starch. The parameters affecting succinate production from cassava starch by E. coli KJ122 were optimized. A succinate concentration of 70.1 ± 0.1 g Ll−1 was produced with a yield of 1.00 ± 0.01 g g−1 substrate and productivity of 0.97 ± 0.01 g L−1h−1 during batch SSF in a 2 L fermentor under optimized conditions. Further improvements in succinate concentration (82.5 ± 0.7 g L−1), yield (1.03 ± 0.01 g g−1 glucose), and average and specific productivities of 1.15 ± 0.01 g L−1h−1, and 456 mg g CDW−1 h−1, respectively, were observed in fed-batch SSF. CONCLUSION: Escherichia coli KJ122 produced a succinate yield of 92% of theoretical maximum and the highest specific productivity ever reported. Succinate production yield and specific productivity from cassava starch in this study are superior to other previously published works. Escherichia coli KJ122 may be used as a biocatalyst for cost-effective succinate production. © 2016 Society of Chemical Industry.