Exploring the internal driving mechanism underlying bacterial community-induced organic component conversion and humus formation during rice straw composting with tricarboxylic acid cycle regulator addition.

The aim of this study was to investigate the effect of tricarboxylic acid (TCA) cycle regulators on CO2 emissions, the conversion of organic components and humus formation during composting. The addition of adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide (NADH) reduced CO2 emissions during rice straw composting. According to co-occurrence networks results, ATP enhanced the connectivity and complexity of the network; NADH enhanced microbial interactions. The different kind of TCA cycle regulators had different effect on humus formation pathway. The structural equation model showed that ATP might promote lignin transformation into humus via the sugar-amine condensation pathway and lignin-protein pathway while NADH may promote cellulose degradation into soluble sugar and organic matter, which are transformed into humus. This work will provide valuable guidance for exploring the mechanism of TCA cycle regulators in promoting organic carbon fixation and reducing inorganic carbon mineralization.