Performance and mechanisms of medium-chain fatty acid production by anaerobic fermentation of food waste without external electron donors

Abstract

This study performed a long-term operation to achieve efficient medium-chain fatty acids (MCFAs) production by anaerobic fermentation of food waste without external electron donors. The results show that total MCFAs reached the highest concentration of 29,886.10 mg COD/L, and n-caproate was the primary product, reaching the current maximum concentration of 28,191.66 mg COD/L. Microbial composition analysis demonstrated Lactobacillus, Bifidobacterium, Sporanaerobacter, and Caproiciproducens constituted the core community throughout the process. Metagenomic analysis suggested that two pathways, reverse β-oxidization (RBO) and fatty acid biosynthesis (FAB), were observed, and the FAB pathway was the main CE pathway. Unclassified_f_Ruminococcaceae and Limosilactobacillus were the main participants in the FAB pathway. This study is expected to provide new insights into MCFAs production from organic waste.