Activation of immobilized Clostridium saccharoperbutylacetonicum N1-4 for butanol production under different oscillatory frequencies and chemical buffers

•Subculture enhances butanol production by immobilized solvent-producing clostridia.•Using acetate as a buffer solution is superior to citrate for ABE fermentation.•High oscillating frequency breaks down the matrix of PVA-sodium alginate.•High oscillating frequency reduces the concentration of solvent-producing clostridia.

This study aimed to investigate the activation of Clostridium saccharoperbutylacetonicum N1-4 immobilized by polyvinyl alcohol (PVA)-sodium alginate to improve butanol production under different oscillatory frequencies and chemical buffers. The results show butanol yields increased from 0.24 to 0.28 g g−1 sucrose consumed by un-subcultured immobilized cells to the level of 0.28–0.35 g g−1 sucrose consumed by subcultured immobilized cells, and there was no discrepancy with the yield of 0.28–0.31 g g−1 sucrose consumed by the free cells. The butanol production rates also increased 5- to 12-fold of those of the un-subcultured immobilized cells when the oscillatory frequencies were controlled from 0 to 3.4 Hz. In addition, an oscillating frequency of 3.4 Hz not only caused a reduction of the free cell concentration in butanol fermentation but also decreased the butanol yield when subcultured immobilized cells were employed. For the effect of the chemical buffers, a butanol production rate of 5243 mg l−1 d−1 for acetate buffer was 3-fold that of citrate. However, the butanol yields of acetate and citrate were not significantly different. The activation via subculture method improves the performance of butanol production by PVA-sodium alginate immobilized Clostridia. Acetate is a preferable buffer chemical for biobutanol production.