2.3. Fermentation set-up
The acid-free sugarcane bagasse hydrolysate (glucose rich) obtained from the second-stage of hydrolysis was used for con- tinuous fermentation with cell recycle in a Bioflow-110 stirred tank bioreactor (New Brunswick, USA) (2-L working volume). A continuous fermentation unit with cell recycle system is shown in Fig. 1A. The bioreactor outlet was connected to a separating funnel from which the cell-enriched bottom stream was recycled to the reactor inlet, while the top supernatant stream from the separating funnel was taken out. A condenser was connected to exhaust gas outlet of the bioreactor to condense the ethanol vapors present in air/N2 stripping gas during fermentation.