Improvement of butanol production from sweet sorghum juice by Clostridium beijerinckii using an orthogonal array design

Optimization of three chemical supplements: CaCO3 (4-10 g/L), (NH4)(2)SO4 (0.50-2.00 g/L) and butyric acid (3-9 g/L) for high levels butanol production by Clostridium beijerinckii TISTR 1461 from sweet sorghum juice was attempted using an L-9 (3(4)) orthogonal array design (OAD). The fermentation was carried out at 37 degrees C in 1-L screw-capped bottles under strictly anaerobic conditions. The OAD results showed that the optimum concentrations of CaCO3, (NH4)(2)SO4 and butyric acid for butanol fermentation were 7, 1.25 and 6g/L, respectively. The butanol concentration (P-b) and productivity (Q(b),) values of the verification experiment under the optimum conditions in a 5-L fermenter were 15.46 g/L and 0.43 g/L.h, respectively at 36 h. The chemicals influencing the Pb and Qb values in descending order were butyric acid > CaCO3 > (NH4)(2)SO4. In the control treatment (sweet sorghum juice without chemical supplementation), the Pb and Qb values were only 0.64 g/L and 0.02 g/L.h, respectively. (C) 2015 Elsevier B.V. All rights reserved.