Shi Mingzi, Song Caihong, Xie Lina, Zhang Guogang, Wei Zimin
Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Sciences, Tianjin Normal University, Tianjin, 300387, China.
College of Life Science, Henan Agricultural University, Zhengzhou, 450000, China.
Environ Microbiome. 2023 May 30;18(1):44. doi: 10.1186/s40793-023-00496-8.
Understanding the functional diversity, composition, and dynamics of microbiome is critical for quality in composting. Denitrifying microbiota, possessing multiple metabolic pathways simultaneously. Denitrification-based biodegradation of aromatic metabolites has been widely applied in the bioremediation of sediments. However, role in biodegradation of denitrifying microbiota in kitchen waste composting remain unclear. In this study, microbiome and metabolome were used to comprehensively decipher the relationship of denitrifying microbiota and aromatic metabolites, and its implication in kitchen waste (KW) composting.
This study was investigated by adjusting moisture content 60% as control test (CK), 70% as denitrification test (DE). In addition, one tests referred as DE + C, which received 10% of biochar to amend denitrification. Results indicated the quantities of denitrification genes narG were 1.22 × 10 copies/g in DE at the 55th day, which were significantly higher than that in CK and DE + C (P < 0.05). Similarly, the abundance of nirK gene also significantly increased in DE (P < 0.05). The relative abundance of denitrification-related microbes in DE was higher than that in CK, DE + C could weaken their abundance. Metabolomics results demonstrated that metabolites were downgraded in aromatic amino acid and catechin metabolic pathways in DE, which were identified as precursors to synthesis key product fulvic acid. The concentrations of fulvic acid dramatically decreased 21.05 mg/g in DE comparison with CK. Biochar addition alleviated the biodegradation of aromatic metabolites and reduced the utilization of fulvic acid. Integrative analyses of metabolomics and microbiome suggested that the microbiota involved in nitrite reduction pathway was vital for the biodegradation aromatic metabolites. Mantel test verified that NO-N, moisture content, eta, environmental factors were important drivers behind the changes in the denitrifying microbiota biodegradation function.
The data confirm the biodegradation function of denitrifying microbiota led to the loss of core product fulvic acid in KW composting, which highlighted the adverse role and implication of denitrification for composting humification. Control of denitrification with biochar was recommended to improve composting quality.
了解微生物群落的功能多样性、组成和动态对于堆肥质量至关重要。反硝化微生物群同时拥有多种代谢途径。基于反硝化作用的芳香族代谢物生物降解已广泛应用于沉积物的生物修复。然而，反硝化微生物群在厨余堆肥生物降解中的作用仍不清楚。在本研究中，利用微生物组学和代谢组学全面解析反硝化微生物群与芳香族代谢物的关系及其在厨余堆肥中的意义。
本研究通过将水分含量调整为60%作为对照试验（CK），70%作为反硝化试验（DE）进行研究。此外，还有一个试验称为DE + C，其中添加10%的生物炭以改善反硝化作用。结果表明，在第55天，DE中反硝化基因narG的数量为1.22×10拷贝/克，显著高于CK和DE + C中的数量（P < 0.05）。同样，nirK基因的丰度在DE中也显著增加（P < 0.05）。DE中与反硝化相关微生物的相对丰度高于CK，DE + C会削弱它们的丰度。代谢组学结果表明，DE中芳香族氨基酸和儿茶素代谢途径中的代谢物被降解，这些代谢物被确定为合成关键产物富里酸的前体。与CK相比，DE中富里酸的浓度显著降低了21.05毫克/克。添加生物炭减轻了芳香族代谢物的生物降解并减少了富里酸的利用。代谢组学和微生物组学的综合分析表明，参与亚硝酸盐还原途径的微生物群对芳香族代谢物的生物降解至关重要。Mantel检验证实，NO-N含量、水分含量、eta等环境因素是反硝化微生物群生物降解功能变化背后的重要驱动因素。
数据证实了反硝化微生物群的生物降解功能导致厨余堆肥中核心产物富里酸的损失，这突出了反硝化作用对堆肥腐殖化的不利作用和影响。建议使用生物炭控制反硝化作用以提高堆肥质量。
