Enhancement of caproate production via carboxylate chain elongation with sequential fermentation facilitated by biochar: A corn stover full-component utilization perspective

In this study, caproate was synthesized from corn stover through sequential fermentation, and biochar was prepared from unhydrolyzable corn stover by pyrolysis to utilize full-component of corn stover. The results indicate that the caproate concentration in the unhydrolyzable corn stover biochar (UCSB) group was 2.2 times higher than that of the control group, and the fermentation start-up time was shortened by 18 days. Mechanistic analysis suggested that the rough surface of UCSB facilitated microbial colonization and reduced product inhibition. Genes expression analysis further demonstrated that UCSB significantly upregulated crucial functional genes responsible for ethanol oxidation and the reverse β -oxidation pathway, ultimately resulting in enhanced caproate production. The successful utilization of UCSB derived from unhydrolyzable solid residue effectively boosted fermentation, leading to a 37 % increase in the carbon utilization efficiency of corn stover. This study offering valuable insights for the high-value and full-component utilization of lignocellulosic biomass.