State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China.
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
Sci Total Environ. 2022 Aug 1;832:155051. doi: 10.1016/j.scitotenv.2022.155051. Epub 2022 Apr 4.
Long-term compost application accelerates organic carbon (C) accumulation and macroaggregate formation in soil. Stable aggregates and high soil organic C (SOC) content are supposed to increase microbiota activity and promote transformation of litter compounds (i.e., cellulose) into SOC. Here, we used C-DNA-stable isotope probing with subsequent high-throughput sequencing to characterize fungal succession and co-occurrence trends during C-cellulose decomposition in aggregate size classes in soils subjected to no fertilizer (control), nitrogen-phosphorus‑potassium (NPK) fertilizers, and compost (Compost) application for 27 years. Ascomycota (mostly saprotrophic fungi) were always highly competitive for cellulose in all aggregate size classes at the early stages of cellulose decomposition (20 days). Compost-treated soil was enriched with Ascomycota compared to the control soil, wherein Sordariomycetes, the majority, strongly dominated the cellulose utilization (C incorporation in DNA). C-labeled fungal communities converged in the Compost soil, with lower abundance and diversity compared with the NPK and control soils. Such convergence led to greater cellulose decomposition, indicating that compost amendment increased the capacity of a few dominant fungal taxa to decompose litter. Compost soil had more C-labeled fungal decomposers in microaggregates and lower fungal decomposers in macroaggregates when compared with the levels in the NPK and control soils. This implies that compost application facilitates fungal colonization towards smaller aggregates. Fungal interactions were reinforced in microaggregates (<250 μm), with more positive associations than those in macroaggregates (>250 μm), indicating greater fungal synergism for recalcitrant resource utilization in microaggregates. The keystone taxa in the co-occurrence networks were not related to cellulose decomposition in microaggregates, but did in macroaggregates. The findings advance a process-based understanding of cellulose utilization by fungal key players based on C and energy availability and the regulation of microbial activity at the aggregate level.
长期施用堆肥会加速土壤中有机碳（C）的积累和大团聚体的形成。稳定的团聚体和高土壤有机碳（SOC）含量应该会增加微生物群落的活性，并促进凋落物化合物（即纤维素）向 SOC 的转化。在这里，我们使用 C-DNA-稳定同位素探测技术，随后对高通量测序进行分析，以描述在经过 27 年未施肥（对照）、氮磷钾（NPK）肥料和堆肥处理的土壤中，不同粒径团聚体中纤维素分解过程中真菌演替和共同发生趋势。在纤维素分解的早期阶段（20 天），子囊菌门（主要是腐生真菌）在所有团聚体粒径中对纤维素的竞争一直很强。与对照土壤相比，堆肥处理的土壤中富集了子囊菌门，其中多数为 Sordariomycetes 强烈主导纤维素的利用（DNA 中的 C 掺入）。C 标记的真菌群落汇聚在堆肥土壤中，与 NPK 和对照土壤相比，其丰度和多样性较低。这种汇聚导致纤维素分解更多，表明堆肥改良增加了少数优势真菌类群分解凋落物的能力。与 NPK 和对照土壤相比，堆肥土壤中小团聚体中有更多的 C 标记真菌分解者，而大团聚体中的真菌分解者则较少。这意味着堆肥的施用促进了真菌在较小团聚体中的定殖。在微团聚体（<250 μm）中，真菌相互作用得到加强，正相关比大团聚体（>250 μm）更多，这表明在微团聚体中，真菌协同作用更大，有利于利用难降解资源。共同发生网络中的关键类群与微团聚体中纤维素的分解无关，但与大团聚体中的纤维素分解有关。这些发现基于 C 和能量的可利用性以及团聚体水平上微生物活性的调控，推进了对真菌关键种在纤维素利用方面的基于过程的理解。
