Butanol production by Clostridium beijerinckii BA101 using cassava flour as fermentation substrate: enzymatic versus chemical pretreatments
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Cassava flour (CF), a cost-effective source of starch, was employed as a substrate for successful acetone-butanol-ethanol (ABE) production by batch-fermentation with Clostridium beijerinckii. The effect of temperature, initial concentration of CF and chemical/enzymatic hydrolysis were studied in a 23 factorial design. Results revealed that temperature and initial concentration of substrate exert a significant effect on ABE production, as well as interactions of temperature with the other variables. Solvent production was maximized when working at 40°C, 60 g l−1 CF and enzymatic pretreatment. An average of 31.38 g l−1 ABE was produced after 96 h, with a productivity of 0.33 g l−1 h−1. A posterior randomized block design (3 × 2) showed that enzymatic hydrolysis (with saccharification periods of 6 h at 60°C) enhances both reducing sugar and solvent production if compared to chemical pretreatments. Average ABE production in this case was 27.28 g l−1, with a productivity of 0.28 g l−1 h−1. Results suggest that CF may be a suitable substrate for industrial ABE production.
KeywordsCassava Butanol ABE fermentation Hydrolysis Clostridium beijerinckii
The authors thank Gerardo Chacón for his support in statistical analyses and Manuel Molina for his helpful suggestions. Technical help from Laura Villalobos and Andrés Chaves is gratefully acknowledged. This work was partially supported by RECOPE.
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