Enhanced butanol production by solvent tolerance Clostridium acetobutylicum SE25 from cassava flour in a fibrous bed bioreactor

- AquaMats AO was used as the immobilization carrier in ABE fermentation.
- The butanol-producing ability of the producing strain SE25 was fairly stable.
- The FBB system is a promising approach for enhancing the butanol productivity.
- The correlation between the biofilm and solvent tolerance was investigated.

To enhance the butanol productivity and reduce the material cost, acetone, butanol, and ethanol fermentation by Clostridium acetobutylicum SE25 was investigated using batch, repeated-batch and continuous cultures in a fibrous bed bioreactor, where cassava flour was used as the substrate. With periodical nutrient supplementation, stable butanol production was maintained for about 360 h in a 6-cycle repeated-batch fermentation with an average butanol productivity of 0.28 g/L/h and butanol yield of 0.32 g/g-starch. In addition, the highest butanol productivity of 0.63 g/L/h and butanol yield of 0.36 g/g-starch were achieved when the dilution rate were investigated in continuous production of acetone, butanol, and ethanol using a fibrous bed bioreactor, which were 231.6% and 28.6% higher than those of the free-cell fermentation. On the other hand, this study also successfully comfirmed that the biofilm can provide an effective protection for the microbial cells which are growing in stressful environment.