Hydrophilic and hydrophobic organic compounds extracted from 13 C-labelled maize residues were incubated with soils to evaluate their mineralization and priming effect (PE) caused by their utilization by microbial groups. Two soils with contrasting soil properties were collected from well-drained upland and water-logged paddy. Mineralization of the 13 C-labelled fractions and their PE were quantified by monitoring the CO 2 efflux and 13 C enrichment during a 40-day incubation. The composition of main microbial groups (bacteria and fungi) involved in the utilization of 13 C-labelled fractions was determined based on phospholipid fatty acids (PLFAs) analysis. At the initial stage (6–24 h), hydrophilic fraction had faster mineralization rate (3.6–70 times) and induced 1.5–10 times stronger PE (positive in upland soil and negative in paddy soil) than those of hydrophobic fraction. The 13 C-PLFAs data showed that the incorporation of hydrophilic fraction into bacteria was 11.4–16.4 times greater than that into fungi, whereas the hydrophobic fraction incorporated into fungi was 1.0–1.5 times larger than that into bacteria at day 2. This indicated greater contributions of r-strategists (fast-growing bacteria) for the uptake of hydrophilic fraction versus K-strategists (slow-growing fungi) for hydrophobic fraction. Compared with K-strategists, the r-strategists possessed a much faster metabolism and thus triggered stronger apparent PE by accelerating microbial biomass turnover, resulting in higher mineralization and stronger PE for the hydrophilic than hydrophobic fraction. The slower and less mineralization of both fractions in paddy than in upland soils is due to the suppression of microbial activity and substrate utilization under flooding. At the end of 40-day incubation, the cumulative mineralization of hydrophilic and hydrophobic fractions was similar. Consequnently, microbial mechanisms underlying the utilization of organic compounds with contrasting solubility (hydrophilic or hydrophobic) are crucial for evaluating the stabilization and destabilization (e.g., priming) processes of soil organic matter.

中文翻译：

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亲水性和疏水性有机基质的不同矿化及其在土壤中的引发作用取决于它们被细菌和真菌的优先利用

从 13 C 标记的玉米残留物中提取的亲水性和疏水性有机化合物与土壤一起培养，以评估它们被微生物群利用所引起的矿化和引发效应 (PE)。从排水良好的高地和积水的稻田中收集了两种土壤性质不同的土壤。通过在 40 天的孵育过程中监测 CO 2 流出和 13 C 富集来量化 13 C 标记级分的矿化及其 PE。基于磷脂脂肪酸 (PLFA) 分析确定了参与 13 C 标记级分利用的主要微生物群（细菌和真菌）的组成。在初始阶段（6-24 小时），亲水部分具有更快的矿化速率（3.6-70 倍）并诱导 1。比疏水部分强 5-10 倍 PE（在旱地土壤中为正，在稻田中为负）。13 C-PLFAs 数据显示，在第 2 天，亲水部分掺入细菌的比例是真菌的 11.4-16.4 倍，而掺入真菌的疏水部分是细菌的 1.0-1.5 倍。这表明更大r-策略者（快速生长的细菌）对亲水部分的吸收与 K-策略者（生长缓慢的真菌）对疏水部分的吸收的贡献。与K-策略剂相比，r-策略剂具有更快的代谢，因此通过加速微生物生物量周转引发更强的表观PE，导致亲水部分比疏水部分的矿化更高和PE更强。与旱地土壤相比，稻谷中这两种部分的矿化更慢且更少，这是由于洪水下微生物活动和底物利用受到抑制。在 40 天的孵化结束时，亲水和疏水部分的累积矿化是相似的。因此，利用具有不同溶解度（亲水性或疏水性）的有机化合物的微生物机制对于评估土壤有机质的稳定和去稳定（例如，引发）过程至关重要。