Abstract：
The substantial release of NH3 during composting leads to nitrogen (N) losses and poses environmental hazards. Additives can mitigate nitrogen loss by adsorbing NH3/NH4, adjusting pH, and enhancing nitrification, thereby improving compost quality. Herein, we assessed the effects of combining bacterial inoculants (BI) (1.5%) with tricalcium phosphate (CA) (2.5%) on N retention, organic N conversion, bacterial biomass, functional genes, network patterns, and enzyme activity during kitchen waste (KW) composting. Results revealed that adding of 1.5%/2.5% (BI + CA) significantly (p < 0.05) improved ecological parameters, including pH (7.82), electrical conductivity (3.49 mS/cm), and N retention during composting. The bacterial network properties of CA (265 node) and BI + CA (341 node) exhibited a substantial niche overlap compared to CK (210 node). Additionally, treatments increased organic N and total N (TN) content while reducing NH4+-N by 65.42% (CA) and 77.56% (BI + CA) compared to the control (33%). The treatments, particularly BI + CA, significantly (p < 0.05) increased amino acid N, hydrolyzable unknown N (HUN), and amide N, while amino sugar N decreased due to bacterial consumption. Network analysis revealed that the combination expanded the core bacterial nodes and edges involved in organic N transformation. Key genes facilitating nitrogen mediation included nitrate reductase (nasC and nirA), nitrogenase (nifK and nifD), and hydroxylamine oxidase (hao). The structural equation model suggested that combined application (CA) and microbial inoculants enhance enzyme activity and bacterial interactions during composting, thereby improving nitrogen conversion and increasing the nutrient content of compost products.
摘要：
堆肥过程中大量释放NH3会导致氮（N）损失并造成环境危害。添加剂可以通过吸附NH3/NH4，调节pH来减轻氮损失，增强硝化，从而提高堆肥质量。在这里，我们评估了细菌接种剂（BI）（1.5％）与磷酸三钙（CA）（2.5％）对N保留的影响，有机N转化，细菌生物量，功能基因，网络模式，以及厨余垃圾(KW)堆肥过程中的酶活性。结果表明，添加1.5％/2.5％（BICA）显着（p<0.05）改善了生态参数，包括pH（7.82），电导率（3.49mS/cm），和N在堆肥过程中的保留。与CK（210节点）相比，CA（265节点）和BICA（341节点）的细菌网络特性表现出明显的生态位重叠。此外,与对照组（33％）相比，处理增加了有机氮和总氮（TN）含量，同时减少了NH4-N的65.42％（CA）和77.56％（BICA）。治疗,特别是BI+CA，显著(p<0.05)增加氨基酸N，可水解未知N（HUN），和酰胺N，而氨基糖N由于细菌消耗而减少。网络分析显示，该组合扩展了参与有机氮转化的核心细菌节点和边缘。促进氮介导的关键基因包括硝酸还原酶（nasC和nirA），固氮酶（nifK和nifD），和羟胺氧化酶(hao)。结构方程模型表明，在堆肥过程中，联合应用（CA）和微生物接种剂可增强酶活性和细菌相互作用，从而提高氮转化率，提高堆肥产品的营养成分。
