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(Δack)-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 ∼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. [ABSTRACT FROM AUTHOR]