초록
<P><B>Abstract</B></P> <P>The Isopropanol-Butanol-Ethanol productivity by solventogenic clostridia can increase when cells are immobilized on low-cost, renewable fibrous materials; however, butanol inhibition imposes the need for dilute sugar solutions (less than40 g/L). To alleviate this problem, the in-situ vacuum product recovery technique was applied to recover IBE in repeated-batch cultivation of <I>Clostridium beijerinckii</I> DSM 6423 immobilized on sugarcane bagasse. Five repeated batch cycles were conducted in a 7-L bioreactor containing P2 medium (∼60 g/L glucose) and bagasse packed in 3D-printed concentric annular baskets. In three cycles, glucose was consumed by 86% on average, the IBE productivity was 0.35 g/L∙h or 30% and 17% higher relative to free- and immobilized (without vacuum)-cell cultures. Notably, the product stream contained 45 g/L IBE. However, the fermentation was unsatisfactory in two cycles. Finally, by inserting a fibrous bed with hollow annuli in a vacuum fermentation, this work introduces the concept of an internal-loop boiling-driven fibrous-bed bioreactor.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>Clostridium beijerinckii</I> DSM 6423 was cultivated under vacuum in repeated batches. </LI> <LI> The cell carrier (sugarcane bagasse) was packed in concentric annular baskets. </LI> <LI> Glucose (∼60 g/L) was consumed by up to 96% in one of the batch cycles. </LI> <LI> The IBE productivity was 0.35 g/L∙h on average during three cycles. </LI> <LI> The concept of an internal-loop boiling-driven fibrous-bed bioreactor was developed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>