Microbes from mature compost to promote bacterial chemotactic motility via tricarboxylic acid cycle-regulated biochemical metabolisms for enhanced composting performance.

This study aims to reveal the underlying mechanisms of mature compost addition for improving organic waste composting. Composting experiments and metagenomic analysis were conducted to elucidate the role of mature compost addition to regulate microbial metabolisms and physiological behaviors for composting amelioration. Mature compost with or without inactivation pretreatment was added to the composting of kitchen and garden wastes at 0%, 5%, 10%, 15%, and 20% (by wet weight) for comparison. Results show that mature compost promoted pyruvate metabolism, tricarboxylic acid (TCA) cycle, and oxidative phosphorylation to produce heat and energy to accelerate temperature increase for composting initiation and biological contaminant removal (>78%) for pasteurization. Energy requirement drives bacterial chemotactic motility towards nutrient-rich regions to sustain organic biodegradation. Nevertheless, when NADH formation exceeded NAD regeneration in oxidative phosphorylation, TCA cycle was restrained to limit continuous temperature increase and recover high intracellular NAD/NADH ratio to secure stable oxidation reactions.