Enhanced direct fermentation from food waste to butanol and hydrogen by an amylolytic Clostridium

This study developed a process using an amylolytic Clostridium sp. strain BOH3 to produce butanol and hydrogen from food waste without enzymatic pretreatment. Strain BOH3, which possesses genes encoding amylases, can produce 14.1 g/L butanol and 16.2 mmol hydrogen from 180 g/L food waste. Protein sequence analysis shows that the amylase in Clostridium sp. strain BOH3 may contain more active sites and possess a higher translation rate than that in Clostridium beijerinckii NCIMB 8052. After calcium was confirmed able to promote the activities of the amylase, the butanol production was improved to 16.6 g/L and the hydrogen production was increased to 18.2 mmol from 180 g/L food waste when external calcium ions were supplemented. Compared to a previous similar study (12.5 g/L), the butanol production is 1.3 - fold of that production. Butanol productivity was also enhanced to 0.17 g/L/h due to the shorter fermentation duration caused by enhanced amylase activities. Thus, Clostridium sp. strain BOH3 is a promising candidate for one-step butanol production using food waste to mitigate environmental sustainability issues. (C) 2020 Elsevier Ltd. All rights reserved.