Continuous production of isopropanol and butanol using Clostridium beijerinckii DSM 6423

Clostridium beijerinckii DSM 6423 was studied using different continuous production methods to give maximum and stable production of isopropanol and n-butanol. In a single-stage continuous culture, when wood pulp was added as a cell holding material, we could increase the solvent productivity from 0.47 to 5.52 g L−1 h−1 with the yield of 54% from glucose. The overall solvent concentration of 7.51 g L−1 (39.4% isopropanol and 60.6% n-butanol) with the maximum solvent productivity of 0.84 g L−1 h−1 was obtained with two-stage continuous culture. We were able to run the process for more than 48 overall retention times without losing the ability to produce solvents.