n-Butanol production from sucrose and sugarcane juice by engineered Clostridium tyrobutyricum overexpressing sucrose catabolism genes and adhE2

The production of n-butanol from sugarcane juice by metabolically engineered Clostridium tyrobutyricum Ct(Delta ack)-pscrBAK overexpressing scr operon genes (scrB, scrA, and scrK) for sucrose catabolism and an aldehyde/alcohol dehydrogenase gene (adhE2) for butanol biosynthesis was studied with corn steep liquor (CSL) as a low-cost nitrogen source. In free cell fermentation, butanol production of similar to 16 g/L at a yield of 0.31 +/- 0.02 g/g and productivity of 0.33 +/- 0.02 g/L.h was obtained from sucrose and yield of 0.24 +/- 0.02 g/g and productivity of 0.30 +/- 0.01 g/L.h from sugarcane juice containing sucrose, glucose and fructose. The fermentation was also studied in a fibrous bed bioreactor (FBB) operated in a repeated batch mode for 10 consecutive cycles in 10 days, achieving an average butanol yield of 0.21 +/- 0.02 g/g and productivity of 0.53 +/- 0.05 g/L.h from sugarcane juice, demonstrating its long-term stability without applying the antibiotic selection pressure. (C) 2017 Elsevier Ltd. All rights reserved.