Product spectrum analysis and microbial insights of medium-chain fatty acids production from waste biomass during liquor fermentation process: Effects of substrate concentrations and fermentation modes

• Main Authors: Zhao, Jihua, Ma, Hongzhi, Wu, Wenyu, Bacar, Mohammed Ali, Wang, Qunhui, Gao, Ming, Wu, Chuanfu, Xia, Changlei, Qian, Dayi, Chong, William Woei Fong, Lam, Su Shiung
• Format: Article
• Published: Elsevier Ltd 2023
• Subjects: TJ Mechanical engineering and machinery
• Online Access: http://eprints.utm.my/105554/; http://dx.doi.org/10.1016/j.biortech.2022.128375

Substrate toxicity would limit the upgrading of waste biomass to medium-chain fatty acids (MCFAs). In this work, two fermentation modes of electro-fermentation (EF) and traditional fermentation (TF) with different concentration of liquor fermentation waste (20%, 40%, 60%) were used for MCFAs production as well as mechanism investigation. The highest caproate (4.04 g/L) and butyrate (13.96 g/L) concentrations were obtained by EF at 40% substrate concentration. TF experiments showed that the substrate concentration above 40% severely inhibited ethanol oxidation and products formation. Compared with TF mode, the total substrates consumption and product yields under EF mode were significantly increased by 2.6%–43.5% and 54.0%–83.0%, respectively. Microbial analysis indicated that EF effectively alleviated substrate toxicity and enriched chain elongation bacteria, particularly Clostridium_sensu_stricto 12, thereby promoting ethanol oxidation and products formation. Caproiciproducens tolerated high-concentration substrates to ensure normal lactate metabolism. This study provides a new way to produce MCFAs from high concentration wastewater.