Recent advances and future prospects for increased butanol production by acetone‐butanol‐ethanol fermentation

Abstract

Presently, several researchers are increasingly focusing on producing butanol as the next‐generation fuel by acetone‐butanol‐ethanol (ABE) fermentation. Butanol has many superior characteristics compared to other biofuels, such as ethanol. However, its production by ABE fermentation faces the challenges of low productivity and yield because of product inhibition and heterofermentation, respectively, and thereby, high costs. Until date, molecular biological techniques and fermentation engineering methods have been applied for high butanol production. Although glucose remains the substrate of choice since traditional research, it is now necessary to substitute glucose derived from edible starch to other substrates from low‐cost feedstock, such as agricultural residue. In addition, ABE‐producing clostridia cannot directly produce butanol from lignocelluloses. Therefore, recent research is focusing on pretreatment and enzymatic saccharification of the complex molecules derived from agricultural residue for use as feedstock in butanol production. This article reviews traditional research, including the metabolism patterns and characteristics of ABE‐producing clostridia. Furthermore, this article describes developments in ABE fermentation with respect to the establishment of highly efficient butanol production processes, such as batch, fed‐batch, and continuous cultures, with the introduction of butanol removal, as well as butanol production from lignocellulosic biomasses or alternative substrates to sugars.

One-pot fermentation of agricultural residues to produce butanol and hydrogen by Clostridium strain BOH3

“…However, a common problem in these strains is that the expression level and activities of sacchraolytic enzymes are too low. Thus, when agricultural residues were used as substrates, they could not be fully utilized [6,7,18]. In contrast, Clostridium strain BOH3 was able to produce 18.7 g/l of butanol from 70 to 75 g/l of glucose [19].…”

“…Enzymes (Cellulase and b-glucosidase) 6.40 g/l ND [9] C. acetobutylicum JB200 Cassava bagasse (100 g/l) Size reduction (Milling) Moist heat (121 C for 30 min)…”

“…However, accumulation of acids in the medium is detrimental to Clostridia. To survive, Clostridia switch to the solventogenesis phase to reassimilate acids to solvents [4,6].…”

Continuous catalytic coupling of raw bioethanol into butanol and higher homologues

“…All these limitations result in low butanol productivity, co-fabrication of additional by-products, high downstream processing cost for butanol recovery, the formation of mixed solvents and relatively low butanol content in the crude product. To develop economical and sustainable processes for bio-based butanol production, attempts were made to modify the metabolic pathways of native Clostridia microorganisms [7][8][9]. Limited attention has been paid to the distillation process in the production of acetone/biobutanol by ABE method and its optymalization [10].…”

Improvement of acetone–butanol–ethanol (ABE) production from switchgrass pretreated with a radio frequency-assisted heating process

“…Bio-based fuels and materials produced from renewable sources have been considered as a solution for this problem [3]. Lignocellulosic biomass such as agricultural residues (corn cob, rice straw, wheat straw, etc.…”