Enhanced cellulosic ethanol production via fed-batch simultaneous saccharification and fermentation of sequential dilute acid-alkali pretreated sugarcane bagasse

This study reports high gravity fed-batch simultaneous saccharification and fermentation (FB-SSF) of sequen-tially pretreated sugarcane bagasse (SCB) for enhanced bioethanol by employing multiple inhibitor tolerant Kluyveromyces marxianus JKH5 C60. FB-SSF with intermittent feeding of SCB (total 20 % solid loading) and enzyme (total dose of 20 FPU/g) at 6 and 12 h resulted in superior bioethanol production at 42 degrees C. Under optimized lab-scale FB-SSF, the maximum ethanol titer, efficiency and productivities were 73.4 +/- 1.2 g/L, 78 % and 3.0 g/L/h, respectively, after 72 h in presence of inhibitors (acetic acid, furfural, and vanillin at 3, 1, and 1 g/ L, respectively). Furthermore, pentose rich dilute acid hydrolysate of SCB was subjected to fermentation by Pichia stipitis NCIM 3499, resulting in ethanol titer of 6.8 g/L. Overall ethanol yield during the developed process was 260.1 g/kg native SCB, which proves industrial potential of the developed bioethanol conversion process.

Automated summary

This study investigates the high gravity fed-batch simultaneous saccharification and fermentation (FB-SSF) of sequentially pretreated sugarcane bagasse (SCB) for enhanced bioethanol production, using the inhibitor tolerant Kluyveromyces marxianus JKH5 C60. The optimized lab-scale FB-SSF, with intermittent feeding of SCB and enzyme, resulted in maximum ethanol titer, efficiency, and productivities of 73.4 g/L, 78%, and 3.0 g/L/h, respectively, after 72 h in the presence of inhibitors. Additionally, fermentation of pentose rich dilute acid hydrolysate of SCB by Pichia stipitis NCIM 3499 yielded an ethanol titer of 6.8 g/L. The overall ethanol yield during the developed process was 260.1 g/kg native SCB, indicating the industrial potential of this bioethanol conversion process.