Comparison of different Vetiver grass pretreatment techniques and their impact on immobilized butanol production by Clostridium beijerinckii TISTR 1461

Abstract

Immobilization of microbe cells has been considered as a potential alternative for enhancing biobutanol productivity through acetone-butanol-ethanol (ABE) fermentation. Vetiver grass (VG; Vetiveria zizanoides) pretreated by sodium hydroxide (NaOH) or sulphuric acid was used as carrier for immobilized Clostridium beijerinckii TISTR 1461 in ABE fermentation. The removal of the lignin and hemicellulose fractions of VG during the pretreatment resulted in structural changes, especially an increased crystallinity and surface area. The VG pretreated with 6% (w/v) NaOH at 120 °C for 6 h had the best potential as a carrier in ABE fermentation, giving a butanol and total ABE concentration of 11.6 g/L and 19.8 g/L, respectively, approximately 1.3-fold greater than that of the free-cell system. The VG samples were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and surface area analyses. © 2021, The Author(s), under exclusive licence to Springer Nature B.V.