Utilization of banana crop residue as an agricultural bioresource for the production of acetone-butanol-ethanol by Clostridium beijerinckii YVU1

Abstract

This study aimed to produce acetone-butanol-ethanol (ABE) using lignocellulosic crop residues as renewable bioresources. Butanol production from banana crop residue (BCR) was studied using a newly isolated solventogenic Clostridium beijerinckii YVU1. BCR is one of the abundant lignocellulosic substrates available in tropical countries containing 4·3 ± 3·5% cellulose, 28·5 ± 3·0% hemicellulose and 20·3 ± 2·6% lignin. The sequential dilute alkali and acid pretreatments solubilized 69% of lignin and 73% of hemicellulose. Ten percent (w/v) of pretreated substrate was subjected to enzymatic saccharification with cellulase, and it was found to release 0·481 ± 0·035 g glucose per g pretreated biomass. In the batch fermentation process, 20·5 g l^-1 ABE (14·0 g l^-1 of butanol, 5·4 g l^-1 of acetone and 1·1 g l^-1 of ethanol) was obtained. The executed fermentation process yielded 0·39 g ABE per g hydrolysate with 0·14 g l^-1 h^-1 of volumetric productivity. On the basis of the results, we believe that sequential alkali and acid pretreatment on the enzymatic hydrolysis for butanol production is indeed a technology with the potential to be applied and newly isolated. C. beijerinckii YVU1 is also a potential candidate organism for butanol production agricultural residues. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrates that a banana crop residue (BCR) can be successfully utilized as an inexpensive and alternative bioresource for the production of acetone-butanol-ethanol (ABE). The sequential pretreatment of BCR with alkali and acid solubilized lignin and hemicellulose leading to high glucose release during enzymatic hydrolysis. A newly isolated Clostridium beijerinckii YVU1 was able to produce comparable amount of ABE with previous reports. Therefore, we can state that the utilization of BCR as substrate for C. beijerinckii YVU1 leads to an economical bioprocess for the microbial production of ABE.

Keywords: Clostridium beijerinckii; anaerobic fermentation; banana crop residue; butanol production; pretreatment.