虻粪二次堆肥生化特性的动态变化趋势及其微生物演替规律

Dynamic features of biochemical property and microbial succession of black soldier fly larvae (Hermetia illucens L) vermicompost during secondary composting

摘要:

[目的] 通过培养试验动态观察了虻粪在后续二次堆肥过程中生化特性的动态变化趋势，研究了堆体微生物生态的动态演替规律，讨论了虻粪二次堆肥的稳定化机理。[方法] 采取盛有虻粪的圆桶埋入大条垛发酵堆体的动态培养试验，在为期49 d的测试期内间隔7 d动态采样，采用16S rRNA高通量测序开展虻粪堆体样品的微生物多样性与群落结构分析以及代谢功能预测。[结果] 虻粪堆体经历2周快速升温至68.7℃后，逐步降温至第49天的37.7℃，总有机碳、溶解性有机质（DOM）、pH分别达到67.3%、18.4 g/kg、8.0。在堆体熟腐过程中，Shannon指数、Simpson指数和Chao1指数等微生物多样性水平均随堆肥进程而快速增加，而后缓慢下降至结束时的7.45、0.98和985。16S rRNA测序发现，Bacteroidetes（拟杆菌门）、Firmicutes（厚壁菌门）、Proteobacteria（变形菌门）与Actinobacteria（放线菌门）等是堆体微生物群落的主要菌群。与此同时，Corynebacteriaceae（棒状杆菌科）从初始的35.7%下降至结束时的6.5%，Flavobacteriaceae（黄杆菌科）则从3.22%逐步增长至12.6%，Porphyromonadaceae（单胞菌科）快速增加至11.5%之后缓慢下降至与初始水平相当的5.1%。PICRUSt预测发现，在整个虻粪堆肥过程中，氨基糖和核苷酸糖代谢、碳固定通路、甲烷代谢等功能平均相对丰度保持较强水平，且均在堆肥中期（第15–35天）出现峰值，后续均呈现下降态势。脂肪代谢、不饱和脂肪酸生物合成代谢、多环芳烃降解以及硫代谢等平均相对丰度较弱的代谢功能呈现先降后升的特征。[结论] 虻粪二次堆肥过程中，物料含水量与DOM快速下降、有机质降解逐步完成以及物料微生物结构与功能趋于稳定等，堆制腐熟后的虻粪生化性质稳定，有利于虻粪有机肥农田再利用。

Abstract:

[Objective] The dynamic trends of biochemical property of black soldier fly (Hermetia illucens L., BSF) larvae vermicompost during the subsequent secondary composting was observed through the culture experiment, and the associated succession of microbial ecology of the BSF vermicompost and the stabilization mechanisms were also discussed. [Methods] Dynamic incubation experiment was conducted in which drums containing BSF vermicompost were buried into a full-scale biomass composting heap, and periodic sampling was conducted at intervals of 7 days during the 49-day testing period. 16S rRNA high-throughput sequencing was used to analyze the bacterial diversity, community structure and metabolic function of BSF vermicompost. [Results] After two weeks of rapid rising to 68.7℃, the temperature of BSF vermicompost gradually decreased to 37.7℃ on the 49th day. When the experiment ended, the total organic carbon, dissolved organic matter (DOM) and pH value reached 67.3%, 18.4 g/kg and 8.0, respectively. The bacterial diversity of Shannon index, Simpson index and Chao1 index increased rapidly with the process of composting, and then decreased slowly to 7.45, 0.98 and 985 at the end. 16S rRNA sequencing shows that dominant phyla included Bacteroidetes, Firmicutes, Proteobacteria and Actinobacteria among the microbial communities. Meanwhile, Corynebacteriaceae decreased from 35.7% at the beginning to 6.5% at the end, Flavobacteriaceae gradually increased from 3.22% to 12.6%, and Porphyromonadaceae increased rapidly to 11.5% and then slowly decreased to 5.1% at the same level as the initial level. PICRUSt predicted that the average relative abundances of amino acid sugar and nucleotide sugar metabolism, carbon fixation pathway, and methane metabolism remained strong throughout the whole secondary composting process of BSF vermicompost, and all of them peaked at the middle stage of composting (day 15-35) then declined. The average relative abundances of fatty acid metabolism, unsaturated fatty acid biosynthesis metabolism, polycyclic aromatic hydrocarbon degradation and sulfur metabolism were shown as decreasing first with following of rising again. [Conclusion] During the secondary composting of BSF vermicompost, the biochemical features of materials and their microbial ecology have significantly changed along with apparent reductions of moisture, DOM, and total organic matters, thus promoting the rapid maturation and stabilization of BSF vermicompost, which is conducive to the farmland reuse of BSF vermicompost as a novel organic fertilizer.