Feasibility of acetone–butanol–ethanol (ABE) fermentation from Amorphophallus konjac waste by Clostridium acetobutylicum ATCC 824

• An ABE fermentation method using Amorphophallus konjac waste was established.
• The effect of alkaloid extraction on fermentation period and butanol concentration was investigated.
• The addition of β-mannanase helped increase the fermentability of konjac waste.
• The fermentation results of SHF and SSF were compared.

Using Amorphophallus konjac waste as a source of fermentable carbohydrate, the feasibility of acetone–butanol–ethanol (ABE) fermentation by Clostridium acetobutylicum ATCC 824 was investigated in this study. Two distinct combination strategies for the enzymatic hydrolysis and fermentation, simultaneous saccharification and fermentation (SSF) and separate hydrolysis and fermentation (SHF), for konjac waste fermentation were compared. β-Mannanase was added to facilitate the hydrolysis of glucomannan and to increase the fermentability of the substrate. The ABE concentration (6.64 g/L) from SSF was less than that from SHF; the result from the control experiment was 4.34 g/L of ABE. SHF obtained a higher production of total ABE solvents (10.95 g/L) with 7.10 g/L of butanol at a productivity rate of 0.30 g/L/h. The effect of the bioactive alkaloid abundant in the konjac waste on ABE fermentation was evaluated. The results indicated that the alkaloid affected the ABE fermentation results when using C. acetobutylicum, and the effective extraction of alkaloids can help to increase the butanol concentration and shorten the fermentation period. Therefore, the utilization of Amorphophallus konjac waste (a low-cost agricultural resource) in ABE fermentation provides an alternative to increase the economic viability of ABE production.

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