Co-amendment of rumen microorganism and bamboo biochar to optimize VFAs synthesis in cornstalk anaerobic fermentation: performance evaluation and mechanism understanding.

This study pioneers the investigation of the fundamental mechanisms by which bamboo biochar (BBC) enhances volatile fatty acids (VFAs) production from cornstalk through anaerobic fermentation by rumen microorganism (RM). The results demonstrate that BBC prepared at 450 °C significantly boosts VFAs production in anaerobic fermentation of cornstalk by 43.8%, compared to the control (CT). In addition, the 450BBC group enhanced lignocellulose degradation efficiency by 99.5% (cellulose), 49.0% (hemicellulose), and 78.0% (lignin) relative to the CT, and 2D-HSQC NMR revealing near-complete disruption of lignin β-O-4 ether and β-β resinol linkages. Solubilization improvements include 21.9% Soluble chemical oxygen demand (SCOD), 20.9% soluble protein, and 10.8% reducing sugar. The research results indicate that the pyrolysis temperature has a significant impact on the redox activity of BBC, which caused by the balance of phenolic hydroxyl and quinone/carbonyl groups. High redox activity can enhance the electron transfer among microorganisms in the anaerobic fermentation system, enrich acid-producing microorganisms, upregulate the expression of key enzyme genes such as acetate kinase and butyrate kinase, and ultimately promote the production of VFAs. The findings propose an innovative and efficient strategy for lignocellulose-to-VFAs conversion.