Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
Sci Total Environ. 2021 Feb 10;755(Pt 2):142595. doi: 10.1016/j.scitotenv.2020.142595. Epub 2020 Oct 2.
The mineralization of soil organic matter is closely related to climate change. Labile organic matter and microbial community are vital intrinsic factors in controlling the mineralization of soil organic matter. Regulation of soil aggregate size on dissolved organic matter (DOM), the cellobiose hydrolyzing microbial community, and their roles in organic matter mineralization remains unclear. The mineralization of organic matter in large macroaggregates (LMA, >2 mm), small macroaggregates (SMA, 0.25-2 mm), and microaggregates (MI, <0.25 mm) from an Ultisol treated with long-term non-fertilizers (Ck), chemical fertilizers (NPK) and animal manure (AM) was observed in this study. The concentration and structure of DOM, activity of β-glucosidase, and the abundance, diversity, and community composition of GH1 (glycoside hydrolase family 1) microbial β-glucosidase encoding genes were investigated. The cumulative CO-C emissions occurred in the order LMA < SMA < MI in each fertilization treatment and followed the sequence Ck < NPK < AM in each size of aggregate. The concentration of DOM in the soil aggregates increased as the aggregate size decreased, while the structural complexity of DOM followed the opposite trend. The activity of β-glucosidase in the smaller aggregates was higher than that in the larger aggregates, and the abundance and diversity of the GH1 microbial β-glucosidase genes generally echoed the same trend. The dominant microbial classes harboring GH1 β-glucosidase genes in the soil aggregates were Actinobacteria, Alphaproteobacteria, Gammaproteobacteria, Flavobacteria, Eurotiomycetes, and Sordariomycetes. The relative abundance of Actinobacteria, Sordariomycetes, and Eurotiomycetes revealed significant differences among the aggregates. Redundancy analysis confirmed that microbial GH1 β-glucosidase community in the soil aggregates was primarily regulated by DOM concentration and pH. Structural equation modelling revealed that soil aggregates mainly regulated the β-glucosidase activity and DOM concentration and then the abundance and diversity of the GH1 microbial β-glucosidase genes in controlling organic matter mineralization.
土壤有机质的矿化与气候变化密切相关。易分解有机质和微生物群落是控制土壤有机质矿化的重要内在因素。土壤团聚体大小对溶解有机质（DOM）、纤维二糖水解微生物群落及其在有机质矿化中的作用的调节尚不清楚。本研究观察了长期不施肥（Ck）、化肥（NPK）和有机肥（AM）处理的赤红壤中大团聚体（LMA，>2mm）、小团聚体（SMA，0.25-2mm）和微团聚体（MI，<0.25mm）中有机质的矿化。研究了 DOM 的浓度和结构、β-葡萄糖苷酶的活性以及 GH1（糖苷水解酶家族 1）微生物β-葡萄糖苷酶编码基因的丰度、多样性和群落组成。累积 CO-C 排放量在每个施肥处理中按 LMA<SMA<MI 的顺序发生，并且在每个团聚体大小中按 Ck<NPK<AM 的顺序发生。土壤团聚体中 DOM 的浓度随着团聚体粒径的减小而增加，而 DOM 的结构复杂性则呈现相反的趋势。较小团聚体中的β-葡萄糖苷酶活性高于较大团聚体，而 GH1 微生物β-葡萄糖苷酶基因的丰度和多样性通常也呈现相同的趋势。土壤团聚体中 GH1β-葡萄糖苷酶基因的优势微生物类群为放线菌、α变形菌、γ变形菌、黄杆菌、子囊菌和散囊菌。土壤团聚体中放线菌、子囊菌和散囊菌的相对丰度存在显著差异。冗余分析证实，土壤团聚体中的微生物 GH1β-葡萄糖苷酶群落主要受 DOM 浓度和 pH 值的调节。结构方程模型表明，土壤团聚体主要通过调节β-葡萄糖苷酶活性和 DOM 浓度来调节 GH1 微生物β-葡萄糖苷酶基因的丰度和多样性，从而控制有机质矿化。
