Soil Biology & Biochemistry最新文献_第6页

Context-dependent contributions of arbuscular mycorrhizal fungi to host performance under global change factors 全球变化因子下丛枝菌根真菌对宿主性能的环境依赖性贡献

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2025-01-04 DOI: 10.1016/j.soilbio.2024.109707

Lennel Camuy-Velez , Ditam Chakraborty , Addisyn Young , Sakshi Paudel , Rylie Elvers , Miranda Vanderhyde , Kelly Walter , Chantal Herzog , Samiran Banerjee

Arbuscular Mycorrhizal Fungi (AMF) contribute to host performance under stress conditions; however, the type and intensity of stress can shape this contribution. Importantly, the benefits of mycorrhizal symbiosis may also vary with the functional group of host plants. It also remains unclear whether multi-species inocula confer greater stress alleviation to hosts or if single-species inocula are sufficient for host resilience. To address these knowledge gaps, we conducted a global meta-analysis of 252 studies from 36 countries on six continents. Our analysis revealed that mycorrhizal associations enhance the phosphorus and nitrogen content of host biomass under these global change factors. However, contrary to previous meta-analyses that found consistently strong impacts of AMF, we found variable contributions of AMF under heat, cold, drought, salinity, pesticide, and heavy metal pollution. Each stress type has a unique impact on the contribution of AMF to host performance, but this impact also varies with the intensity of stress. Single-species AMF inocula contribute more significantly to host performance under stress compared to multi-species inocula. We also show that the contribution of AMF to plant growth response significantly varies across different plant functional groups, with grasses and legumes significantly benefiting from mycorrhizal associations under global change factors. Overall, this study highlights that the contribution of AMF to host performance under stress is highly context-dependent and influenced by various factors, including the type and intensity of stress, the type of inocula, and the functional groups of host plants. Thus, our meta-analysis can help develop hypotheses that can be tested with mechanistic experiments to gain a better understanding of the synergistic relationship between AMF and host plants in overcoming stress.

丛枝菌根真菌（AMF）对应激条件下宿主的生产性能有贡献；然而，压力的类型和强度会影响这种贡献。重要的是，菌根共生的益处也可能因寄主植物的功能群而异。目前还不清楚的是，多物种接种是否能更好地减轻宿主的压力，或者单物种接种是否足以增强宿主的恢复力。为了解决这些知识差距，我们对来自六大洲36个国家的252项研究进行了全球荟萃分析。结果表明，在这些全球变化因子的影响下，菌根联系会提高寄主生物量的磷和氮含量。然而，与先前的荟萃分析相反，我们发现AMF在热、冷、干旱、盐度、农药和重金属污染下的贡献是可变的。每种应力类型对AMF对宿主性能的贡献都有独特的影响，但这种影响也随应力的强度而变化。与多菌种接种相比，单菌种接种对应激条件下宿主生产性能的贡献更显著。我们还发现，AMF对植物生长响应的贡献在不同的植物功能群中存在显著差异，禾草和豆科植物在全球变化因子下显著受益于菌根关联。总体而言，本研究强调AMF对胁迫下寄主性能的贡献高度依赖于环境，并受到多种因素的影响，包括胁迫类型和强度、接种类型和寄主植物的功能群。因此，我们的荟萃分析可以帮助建立假说，这些假说可以通过机械实验进行测试，以更好地了解AMF和寄主植物在克服胁迫方面的协同关系。

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引用次数: 0

Soil pH promoted respiration is stimulated by exoenzyme kinetic properties for a Pinus tabuliformis forest of northern China 油松林土壤pH促进呼吸作用的外酶动力学特性研究

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2025-01-03 DOI: 10.1016/j.soilbio.2025.109709

Mengyao Xu , Zhiyong Zhou , Yinhua Guo , Ying Shen , Huan Zhang , Qiang Yu

The trends in 21st century climate change will be largely modulated by the amount of carbon respired via the enzymatic depolymerization of soil organic carbon (SOC). As soil pH serves as a key indicator of global change, understanding how soil respiration responds to pH induced changes in enzyme kinetic properties will provide valuable insights into the feedback of soil carbon to climate change. In a Pinus tabuliformis forest of northern China, a soil pH gradient ranging from 4.91 to 7.89 was constructed by applying ammonium nitrate at rates of 5, 10, 20, and 40 g N m⁻² yr⁻¹ (N5, N10, N20, and N40) and lime at rates of 50, 100, 200, and 400 g m⁻² yr⁻¹ (L50, L100, L200, and L400) since 2015. In August 2022, soil basal respiration, the β-glucosidase (BG) activity, and soil microbial properties were measured. Results revealed that soil basal respiration increased from 1.46 μmol CO₂ m⁻² s⁻¹ in N40 treatment to 2.36 CO₂ m⁻² s⁻¹ in L400 treatment, while the binding affinity of BG rose from 0.018 to 0.032 under the same treatments. The maximum activity of BG decreased from 119.82 nmol MUB·h⁻¹·g⁻¹ SOM in N40 treatment to 66.80 nmol MUB·h⁻¹·g⁻¹ SOM in L400 treatment. The temperature sensitivity of soil respiration showed a bell-shaped response to soil pH, with an optimal pH of about pH 6.7. Our findings demonstrated that it was the binding affinity instead of the activity of BG that positively promoted soil respiration across the established soil pH gradient. The underpinning mechanisms linking soil respiration with enzyme functions were ascribed to the soil acid-base microenvironment, which affected the bioavailability of key nutrient and the content of soil inorganic nitrogen. Additionally, these results will improve the understanding of enzymatic mechanisms in driving the biogeochemical cycle of SOC.

21世纪气候变化的趋势将在很大程度上受到土壤有机碳酶解聚合所呼吸的碳量的调节。由于土壤pH值是全球变化的关键指标，了解土壤呼吸如何响应pH值引起的酶动力学性质的变化将为土壤碳对气候变化的反馈提供有价值的见解。2015年以来，通过施用5、10、20和40 g N - m-2年-1 （N5、N10、N20和N40）的硝酸铵和施用50、100、200和400 g N - m-2年-1 （L50、L100、L200和L400）的石灰，在中国北方油松森林中构建了4.91 ~ 7.89的土壤pH梯度。2022年8月，测定了土壤基础呼吸、β-葡萄糖苷酶（BG）活性和土壤微生物特性。结果表明，N40处理的土壤基础呼吸从1.46 μmol CO2 m-2 s-1增加到L400处理的2.36 μmol CO2 m-2 s-1，而BG的结合亲和力从0.018增加到0.032。BG的最大活性由N40处理的119.82 nmol MUB·h-1·g-1 SOM降至L400处理的66.80 nmol MUB·h-1·g-1 SOM。土壤呼吸的温度敏感性对土壤pH呈钟形响应，最佳pH值约为pH 6.7。我们的研究结果表明，在既定的土壤pH梯度中，是结合亲和力而不是BG的活性积极促进了土壤呼吸。土壤酸碱微环境影响土壤关键养分的生物有效性和土壤无机氮含量，是土壤呼吸与酶功能联系的基础机制。此外，这些结果将提高对酶驱动有机碳生物地球化学循环机制的理解。

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引用次数: 0

Heterotrophic nitrification in soils: Approaches and mechanisms 土壤中的异养硝化作用：途径和机制

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-12-31 DOI: 10.1016/j.soilbio.2024.109706

Elizaveta P. Pulikova , Andrey V. Gorovtsov , Yakov Kuzyakov , Konstantin A. Demin , Tatiana M. Minkina , Vishnu D. Rajput

Studies on nitrification, a crucial process of biogeochemical N cycling, have traditionally focused on autotrophic microorganisms. Recent discoveries, however, highlight the importance of heterotrophic nitrification as a key to N cycling, particularly in acidic soils. While molecular approaches have advanced our understanding of the key players in autotrophic nitrification, the biochemical mechanisms and corresponding genes of heterotrophic nitrification are nearly unknown. First, we reviewed the advantages and limitations of existing approaches to analyze heterotrophic nitrification in soils. ¹⁵N labeling of organic compounds (e.g. amino acids) allows to determine solely the nitrification of organic N. Because many bacteria have similar autotrophic nitrification enzymes that oxidize inorganic N, it is necessary to inhibit autotrophic nitrification to determine the heterotrophic N nitrification activity by ¹⁵N techniques. The use of existing inhibitors, however, can mislead the conclusions because not all inhibitors stop autotrophic nitrification completely, and some can decrease heterotrophic nitrification. Their effects strongly depend on the composition of the nitrifier community and soil properties. The use of modern molecular approaches is limited by suitable genetic biomarkers. Second, we propose the following methods to investigate heterotrophic nitrification processes: i) isolation and purification of heterotrophic nitrification enzymes, followed by determination of the amino acid sequence of proteins to design genetic markers; ii) use of DNA-based stable isotopes (¹³C, ¹⁵N); iii) combining fluorescence in situ hybridization with microautoradiography (¹⁴C) to determine the composition of heterotrophic nitrifier communities; and iv) scheme to select autotrophic nitrification inhibitors. We suggest to improve the existing approaches to shed new light on the processes of heterotrophic nitrification, which can reach 99% of total nitrification in forest soils and strongly affect N stocks and fluxes in terrestrial ecosystems.

硝化作用是生物地球化学氮循环的一个重要过程，传统上对其研究主要集中在自养微生物上。然而，最近的发现强调了异养硝化作为氮循环关键的重要性，特别是在酸性土壤中。虽然分子方法已经提高了我们对自养硝化的关键参与者的理解，但异养硝化的生化机制和相应的基因几乎是未知的。首先，综述了现有土壤异养硝化分析方法的优点和局限性。有机化合物（如氨基酸）的15N标记允许单独确定有机N的硝化作用，因为许多细菌具有类似的自养硝化酶来氧化无机N，因此有必要抑制自养硝化作用，以确定异养N硝化活性。然而，现有抑制剂的使用可能会误导结论，因为并非所有抑制剂都能完全阻止自养硝化，有些抑制剂可以减少异养硝化。它们的作用在很大程度上取决于氮肥群落的组成和土壤性质。现代分子方法的使用受到合适的遗传生物标志物的限制。其次，我们提出了以下方法来研究异养硝化过程：i)分离纯化异养硝化酶，然后确定蛋白质的氨基酸序列，设计遗传标记；ii)使用基于dna的稳定同位素（13C, 15N）；iii)结合荧光原位杂交和显微放射自显影（14C）测定异养硝化菌群落组成；iv)自养硝化抑制剂的选择方案。异养硝化作用可达到森林土壤总硝化作用的99%，并对陆地生态系统氮储量和通量产生强烈影响。

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引用次数: 0

Spatiotemporal dynamics of reactive oxygen species in the detritusphere and their critical roles in organic carbon mineralisation 碎屑层中活性氧的时空动态及其在有机碳矿化中的关键作用

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-12-30 DOI: 10.1016/j.soilbio.2024.109700

Kangjie Yang , Jinbo Liu , Zhiqiang Wang , Kecheng Zhu , Bin Jia , Huiqiang Yang , Jianjun Qin , Jia Xie , Junaid Latif , Fuhao Liu , Yanpei Li , Na Chen , Hanzhong Jia

Reactive oxygen species (ROS) are recognised as important drivers of biogeochemical processes. However, the dynamics and distribution of ROS and their effects on carbon emissions in the detritusphere remain elusive. Herein, we visualised the production of ROS in situ (i.e. superoxide radical, O₂^•−; hydrogen peroxide, H₂O₂; and hydroxyl radical, ^•OH) in the detritusphere using a ROS-trapping agar gel, of which the contents gradually increased and then decreased with residue decay. Spatially, O₂^•− content gradually decreased with increasing distance from residue, whereas H₂O₂ content increased. Interestingly, the content of ^•OH increased from 3.2 to 4.3 μmol kg⁻¹ and decreased from 6.9 to 3.9 μmol kg⁻¹ with increasing distance from residue after incubation for 3 d and 24 d, respectively. Spearman correlation analysis revealed that O₂^•−production was closely related to the oxidation of water-soluble phenols by phenol oxidase. In contrast, H₂O₂ production correlated with microbial abundance, suggesting that microorganisms served as primary drivers of H₂O₂ production in the detritusphere. Results from incubation experiment suggest that the dominant drivers of ^•OH production shifted from Fe(II) to water-extractable organic carbon (WEOC) between day 3 and day 24 of residue decomposition. Furthermore, autoclaving reduced ^•OH content regardless of Fe(II) or WEOC presence, highlighting the important role of microorganism in ^•OH generation. The formed ROS significantly influenced the mineralisation of organic carbon (OC, P < 0.05), and the contributions varied by type of ROS. Specifically, ROS quenching experiments showed that ^•OH and O₂^•− stimulated OC mineralisation by 15% and 4%, respectively, while H₂O₂ reduced it by 18%. The obtained information highlights detritusphere as pervasive yet previously underestimated hotspots for ROS production, which has significant implication for soil OC mineralisation and priming effect.

活性氧（ROS）被认为是生物地球化学过程的重要驱动力。然而，活性氧的动态和分布及其对碎屑层碳排放的影响仍然难以捉摸。在此，我们可视化了原位ROS的产生(即超氧自由基，O2•−；过氧化氢，H2O2；和羟基自由基（•OH），随着残渣的腐烂，其含量先增加后减少。从空间上看，O2•−含量随着离残渣距离的增加而逐渐降低，而H2O2含量则逐渐增加。培养3 d和24 d后，随着离残基距离的增加，•OH含量分别从3.2 μmol kg-1上升到4.3 μmol kg-1，从6.9 μmol kg-1下降到3.9 μmol kg-1。Spearman相关分析表明，O2•−的产生与酚氧化酶对水溶性酚的氧化密切相关。相比之下，H2O2产量与微生物丰度相关，表明微生物是碎屑层中H2O2产量的主要驱动因素。孵育实验结果表明，在残渣分解的第3天至第24天之间，•OH生成的主要驱动因素从Fe（II）转变为水萃取有机碳（WEOC）。此外，无论是否存在Fe（II）或WEOC，高压灭菌都降低了•OH含量，这突出了微生物在•OH生成中的重要作用。形成的活性氧显著影响有机碳矿化(OC, P <；0.05)，不同类型活性氧的贡献不同。具体来说，ROS猝灭实验表明，•OH和O2•−分别刺激了15%和4%的OC矿化，而H2O2则减少了18%。获得的信息强调碎屑层是普遍存在的，但以前被低估的ROS生产热点，这对土壤OC矿化和启动效应具有重要意义。

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引用次数: 0

Earthworms buffer the impacts of nitrogen enrichment on energy dynamics of soil micro-food webs 蚯蚓缓冲了富氮对土壤微食物网能量动态的影响

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-12-30 DOI: 10.1016/j.soilbio.2024.109705

Bingbing Wan , Andrew D. Barnes , Mingyu Li , Yuanyuan Song , Qian Yang , Xiaoyun Chen , Feng Hu , Manqiang Liu

Anthropogenic nitrogen (N) enrichment is an important driver of global soil biodiversity loss, particularly for large-bodied consumers at the higher trophic levels of food webs. This driver is predicted to vastly impact the energy dynamics in soil food webs, which underpin ecosystem functioning and services. Yet, we still lack empirical evidence about how N-enrichment and the loss of large consumers (e.g., earthworms) might affect the energetic structure of soil food webs and associated ecosystem functions. Here, based on a 4-year field manipulation experiment, we explore the interactive effects of increasing N inputs and earthworms on the energy dynamics and trophic functions (i.e., herbivory, decomposition and predation) of soil micro-food webs. Our results revealed that after earthworm removal, total and average energy flux of soil micro-food webs decreased linearly as N input increased, largely explained by functional diversity. Specifically, decomposition, as indicated by energy flux through decomposers, initially decreased and then increased with increasing N inputs, while herbivory and predation decreased linearly. However, earthworm activities mitigated such negative effects of N enrichment on energy dynamics, maintaining total and average energy flux largely unchanged across the N gradient. Along with functional diversity, we also found that earthworm-induced changes in taxonomic diversity was positively correlated with total and average energy flux, possibly attributed to facilitating species interactions and thus fostering energy transfers. These findings emphasize the importance of protecting large consumers as biotic buffers to counteract biodiversity loss and maintain trophic functions under future N enrichment.

人为氮(N)富集是全球土壤生物多样性丧失的重要驱动因素，特别是对于食物网中较高营养水平的大型消费者而言。预计这一驱动因素将极大地影响土壤食物网中的能量动态，而土壤食物网是生态系统功能和服务的基础。然而，我们仍然缺乏关于n富集和大型消费者（如蚯蚓）的损失如何影响土壤食物网的能量结构和相关生态系统功能的经验证据。通过为期4年的田间操作试验，研究了增加氮素投入和蚯蚓对土壤微食物网能量动态和营养功能（即草食、分解和捕食）的交互作用。结果表明，去除蚯蚓后，土壤微食物网总能量通量和平均能量通量随N输入的增加呈线性下降，这在很大程度上与功能多样性有关。具体而言，随着N输入的增加，通过分解者的能量通量表现为先减少后增加，而食草性和捕食性呈线性减少。然而，蚯蚓活动减轻了氮富集对能量动态的负面影响，使总能量通量和平均能量通量在整个N梯度上基本保持不变。除了功能多样性外，我们还发现蚯蚓诱导的分类多样性变化与总能量通量和平均能量通量呈正相关，这可能是由于蚯蚓促进了物种相互作用，从而促进了能量转移。这些发现强调了保护大型消费者作为生物缓冲物的重要性，以抵消生物多样性的丧失，并在未来N富集的情况下维持营养功能。

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引用次数: 0

Multitrophic interactions support belowground carbon sequestration through microbial necromass accumulation in dryland biocrusts 多营养相互作用支持地下碳固存通过微生物坏死团积累在旱地生物壳

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-12-30 DOI: 10.1016/j.soilbio.2024.109708

Jia Shi , Lijia Lu , Jingxi Zang , Yuanze Sun , Jianguo Tao , Zelong Zhao , Xiang Wang , Jie Wang

Belowground organisms play essential roles in biogeochemical cycling of carbon. However, it remains unknown how species interactions across multiple trophic levels influence soil carbon sequestration. Biological soil crusts (biocrusts) comprise multiple trophic groups, forming an ideal model system to study species interactions in natural communities. This study explored the critical role of multitrophic interactions in shaping the accumulation of microbial necromass carbon (MNC), comparing biocrust-covered and bare soils in the dryland ecosystem of the Loess Plateau. Amino sugars were used as indicators of soil microbial necromass, and environmental DNA sequencing was used to characterize multitrophic communities in soil samples. Biocrust-associated soils exhibited 2.5 times higher MNC than bare soils, with bacterial necromass carbon (BNC) constituting a larger proportion of soil organic carbon than fungal necromass carbon (FNC). Greater network complexity and more frequent within-trophic associations (WTAs) were observed for bare soils. The proportion of negative WTAs was negatively correlated with MNC, whereas the proportion of cross-trophic associations (CTAs) was positively correlated with MNC. Community composition, hierarchical interactions, and network complexity all shaped microbial necromass carbon accumulation. This study illustrates a novel mechanism contributing to carbon sequestration in dryland ecosystems, wherein multitrophic interactions within the soil micro-food web regulate microbial necromass accumulation, and sheds light on the dynamics and stabilization of soil microbial necromass.

地下生物在碳的生物地球化学循环中起着重要作用。然而，物种间的相互作用如何影响土壤碳固存仍是未知的。生物土壤结皮包含多个营养类群，是研究自然群落中物种相互作用的理想模型系统。本研究通过对黄土高原干旱生态系统覆盖土壤和裸露土壤进行比较，探讨了多营养相互作用在形成微生物坏死体碳（MNC）积累中的关键作用。利用氨基糖作为土壤微生物坏死的指标，利用环境DNA测序来表征土壤样品中的多营养群落。生物结皮伴生土壤的有机质碳含量是裸地的2.5倍，细菌坏死体碳（BNC）占土壤有机碳的比例高于真菌坏死体碳（FNC）。裸地土壤具有更大的网络复杂性和更频繁的营养内关联（WTAs）。负WTAs比例与MNC呈负相关，而跨营养关联比例与MNC呈正相关。群落组成、层次相互作用和网络复杂性都形成了微生物坏死团的碳积累。本研究揭示了旱地生态系统碳固存的新机制，其中土壤微食物网内的多营养相互作用调节了土壤微生物坏死团的积累，并揭示了土壤微生物坏死团的动力学和稳定性。

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引用次数: 0

Spatial heterogeneity of high-affinity H2 oxidation activity in agricultural soil profile 农业土壤高亲和力H2氧化活性的空间异质性

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-12-28 DOI: 10.1016/j.soilbio.2024.109703

Lijun Hou , Philippe Constant , Joann K. Whalen

Soil H₂ oxidizing bacteria metabolize H₂ from the atmosphere, but soil carbon substrates and environmental factors influence their distribution in the soil profile. We conducted a field survey of the spatial distribution of H₂ content and high-affinity H₂ oxidation activity in the soil profile (5 cm, 15 cm, and 35 cm) and between the soybean rhizosphere and bulk soil. We found the H₂ content declined exponentially with soil depth, but potential H₂ oxidation activity was consistent at all soil depths. The rhizosphere soil had 66% more high-affinity H₂ oxidation activity than bulk soil. Simultaneous presence of H₂ and carbon likely facilitates mixotrophic growth of H₂ oxidizing bacteria in the rhizosphere.

土壤H2氧化菌对大气中的H2进行代谢，但土壤碳基质和环境因子影响其在土壤剖面中的分布。对土壤剖面（5 cm、15 cm和35 cm）以及大豆根际和块土之间H2含量和高亲和力H2氧化活性的空间分布进行了实地调查。H2含量随土壤深度呈指数下降，但潜在的H2氧化活性在所有土壤深度都是一致的。根际土壤的高亲和H 2氧化活性比散装土壤高66%。同时存在H2和碳可能促进H2氧化细菌在根际的混合营养生长。

引用次数: 0

Arbuscular mycorrhizal fungal highways – What, how and why? 丛枝菌根真菌高速公路-什么，如何和为什么？

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-12-28 DOI: 10.1016/j.soilbio.2024.109702

Caroline Krug Vieira , Matheus Nicoletti Marascalchi , Martin Rozmoš , Oldřich Benada , Valeriia Belova , Jan Jansa

Arbuscular mycorrhizal (AM) fungal structures, such as spores, vesicles, extra- and intra-radical hyphae, are home to diverse communities of prokaryotic (bacterial and archaeal) taxa and can have significant impact on the movement and behavior of those microbes within the soil. The ability to disperse via fungal hyphae, known as the fungal highway effect, was first observed in ectomycorrhiza and later in other fungal groups. This effect may benefit soil prokaryotes allowing them to explore new microhabitats in soil, offering advantages such as improved nutrient access, enhanced dispersal and colonization. Although the term “fungal highways” is well established, there still are only few studies that address the partner interactions and movement of microorganisms through the hyphal networks when referring to AM fungi. Bacteria can colonize the surfaces of hyphae and form biofilms that provide protection for both the bacteria and the fungus, influence the nutrient cycles, giving the bacteria access to resources transported by the fungus. Bacteria movement on AM fungal hyphae is facilitated by several mechanisms, including physical transport along the hyphal networks, swimming within the continuous water films that develop along the hyphal surfaces, and chemotaxis, where the bacteria move towards or away from specific chemical signals. Overall, the interactions between bacteria and AM fungi appears as a dynamic and complex process. Yet, we still do not know much about the influence of soil properties, plant age and species, seasonality, soil management and different climate with respect to AM fungal highways and microbiomes. Here, we review the current knowledge on prokaryotic movement through AM fungal hyphosphere and the possible factors that could affect it. Future research needs to elucidate mechanisms involved in the recruitment and/or migration of microbes in the AM fungal hyphosphere. Understanding these interactions may eventually help developing more sustainable agricultural practices and/or support environmental conservation.

丛枝菌根（AM）真菌结构，如孢子、囊泡、根外菌丝和根内菌丝，是原核生物（细菌和古细菌）分类群的家园，对土壤中微生物的运动和行为有重要影响。通过真菌菌丝传播的能力，被称为真菌高速公路效应，首先在外菌根中被观察到，后来在其他真菌群中也被观察到。这种效应可能有利于土壤原核生物，使它们能够在土壤中探索新的微栖息地，提供诸如改善养分获取，增强扩散和定植等优势。尽管“真菌高速公路”一词已经确立，但当涉及AM真菌时，仍然只有少数研究涉及微生物通过菌丝网络的伴侣相互作用和运动。细菌可以在菌丝表面定植并形成生物膜，为细菌和真菌提供保护，影响营养循环，使细菌能够获得真菌运输的资源。AM真菌菌丝上的细菌运动受到几种机制的促进，包括沿着菌丝网络的物理运输，在菌丝表面形成的连续水膜中游泳，以及趋化性，细菌向特定化学信号移动或远离。总之，细菌与AM真菌之间的相互作用是一个动态而复杂的过程。然而，土壤性质、植物年龄和种类、季节、土壤管理和不同气候对AM真菌高速公路和微生物组的影响尚不清楚。在此，我们对AM真菌丝球的原核运动及其可能的影响因素进行了综述。未来的研究需要阐明AM真菌丝球中微生物招募和/或迁移的机制。了解这些相互作用可能最终有助于发展更可持续的农业实践和/或支持环境保护。

{"title":"Arbuscular mycorrhizal fungal highways – What, how and why?","authors":"Caroline Krug Vieira , Matheus Nicoletti Marascalchi , Martin Rozmoš , Oldřich Benada , Valeriia Belova , Jan Jansa","doi":"10.1016/j.soilbio.2024.109702","DOIUrl":"10.1016/j.soilbio.2024.109702","url":null,"abstract":"<div><div>Arbuscular mycorrhizal (AM) fungal structures, such as spores, vesicles, extra- and intra-radical hyphae, are home to diverse communities of prokaryotic (bacterial and archaeal) taxa and can have significant impact on the movement and behavior of those microbes within the soil. The ability to disperse via fungal hyphae, known as the fungal highway effect, was first observed in ectomycorrhiza and later in other fungal groups. This effect may benefit soil prokaryotes allowing them to explore new microhabitats in soil, offering advantages such as improved nutrient access, enhanced dispersal and colonization. Although the term “fungal highways” is well established, there still are only few studies that address the partner interactions and movement of microorganisms through the hyphal networks when referring to AM fungi. Bacteria can colonize the surfaces of hyphae and form biofilms that provide protection for both the bacteria and the fungus, influence the nutrient cycles, giving the bacteria access to resources transported by the fungus. Bacteria movement on AM fungal hyphae is facilitated by several mechanisms, including physical transport along the hyphal networks, swimming within the continuous water films that develop along the hyphal surfaces, and chemotaxis, where the bacteria move towards or away from specific chemical signals. Overall, the interactions between bacteria and AM fungi appears as a dynamic and complex process. Yet, we still do not know much about the influence of soil properties, plant age and species, seasonality, soil management and different climate with respect to AM fungal highways and microbiomes. Here, we review the current knowledge on prokaryotic movement through AM fungal hyphosphere and the possible factors that could affect it. Future research needs to elucidate mechanisms involved in the recruitment and/or migration of microbes in the AM fungal hyphosphere. Understanding these interactions may eventually help developing more sustainable agricultural practices and/or support environmental conservation.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"202 ","pages":"Article 109702"},"PeriodicalIF":9.8,"publicationDate":"2024-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142888929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Do chromogenic assays of soil enzyme activities need buffers? More disadvantages than advantages of modified universal buffer in the para-nitrophenyl-based assay of phosphomonoesterase and β-glucosidase activities 土壤酶活性显色分析需要缓冲液吗？改良通用缓冲液在以对硝基苯为基础的磷酸单酯酶和β-葡萄糖苷酶测定中缺点多于优点

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-12-28 DOI: 10.1016/j.soilbio.2024.109704

Chongyang Li , Jordon Wade , Kelly Vollbracht , Diane G. Hooper , Skye A. Wills , Andrew J. Margenot

Buffers are commonly employed in soil enzyme activity assays to maintain a constant pH during the assay incubation, but soils are already buffered and buffer can alter apparent V_max and K_m. To test for potential artifacts of buffer on soil enzyme activities, we selected 32 soils to furnish a broad range of physicochemical characteristics and assayed soil β-glucosidase (BG) and phosphomonoesterase (PME) activities at varied substrate concentrations in water or in modified universal buffer (MUB). The pH of assays differed by up to 1.6 units from the measured soil pH (1:2, m/v in water), but MUB did not maintain pH any better than water. Compared to water, MUB generally suppressed activities (by ≈31%), apparent V_max (by ≈32%) and K_m (by ≈52%) of PME, but yielded similar activities (by ≈4% difference) and apparent V_max (by ≈9% difference) for BG. Soils with higher pH tended to have larger degree of PME actvity suppression by MUB compared to water. Based on the best practice of using a substrate concentration that is 5 × K_m to approximate substrate saturation of the enzyme, the median substrate requirement to assay PME across the 32 soils was ≈50 mM g⁻¹ in water and 25 mM g⁻¹ in MUB. Regardless of assay matrix, the commonly employed PME substrate concentration of 10 mM g⁻¹ (e.g., Tabatabai, 1994) is insufficient for accurate activity assays (i.e., activities assayed at V_max). In contrast, for BG assays the commonly used pNP-linked substrate concentration of 10 mM g⁻¹ appears appropriate for most soils with a median substrate requirement of ≈4 mM g⁻¹ in water and ≈6 mM g⁻¹ in MUB. Our results support previous propositions that buffers are unnecessary for assaying soil enzyme activities and may alter apparent kinetic parameters (K_m, V_max). Potential soil- and enzyme-specific substrate requirements should be determined a priori to ensure accurate measurements of enzyme activities in soils.

缓冲液通常用于土壤酶测定，以在测定孵育期间保持恒定的pH值，但土壤已经被缓冲，缓冲液可以改变表观Vmax和Km。为了测试缓冲液对土壤酶活性的潜在影响，我们选择了32种土壤，提供了广泛的理化特征，并在不同的底物浓度下测定了土壤β-葡萄糖苷酶（BG）和磷酸单酯酶（PME）的活性，这些底物浓度分别是在水中或改性通用缓冲液（MUB）中。测定的pH值与测定的土壤pH值（1:2，m/v在水中）不同（高达1.6个单位），但MUB并不比水更好地维持pH值。与水相比，MUB通常抑制PME的活性（减少~ 31%）、表观Vmax（减少~ 32%）和Km（减少~ 52%），但对BG的活性（减少~ 4%）和表观Vmax（减少~ 9%）相似。与水中相比，pH值较高的土壤中MUB中PME活性的抑制程度较大。根据使用底物浓度5×Km作为酶的底物饱和度的最佳实践，在这32种土壤中测定PME的中位底物要求在水中≈50 mM g-1，在MUB中为25 mM g-1。无论基质类型如何，通常使用的PME底物浓度为10 mM g-1（例如，Tabatabai, 1994）不足以进行准确的活性测定。相比之下，对于BG分析，通常使用的10 mM g-1的pNP-linked底物浓度似乎适用于大多数土壤，水中和MUB中对底物的中值要求分别为~ 4 mM g-1和~ 6 mM g-1。我们的研究结果支持了先前的观点，即缓冲液对于测定土壤酶活性是不必要的，并且可以改变表观动力学参数（Km, Vmax）。潜在的土壤和酶特异性底物要求应事先确定，以确保准确测量土壤中的酶活性。

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引用次数: 0

In pursuit of soil P mineralization: A review and synthesis of radioisotopic labeling techniques 土壤磷矿化研究：放射性同位素标记技术综述与综合

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-12-28 DOI: 10.1016/j.soilbio.2024.109701

Chongyang Li , Jordon Wade , Andrew J. Margenot

Predicting soil phosphorus (P) bioavailability requires an understanding of organic P mineralization (P_min) but assessing P_min rates is challenging. Recent advances in radioisotopic P labeling enable estimates of P_min rates in soil. However, there is yet no standardization of radioisotopic dilution methods, potentially compromising comparison of results among studies. We conducted a systematic literature search to (1) synthesize the varying procedures among different studies, (2) compare the soil P_min results obtained via the two most commonly used approaches, isotope exchangeable kinetics (IEK) and isotope pool dilution (IPD), and (3) address the methodological advantages and limitations of IEK and IPD. We identified and analyzed 98 studies, and found large discrepancies in study-specific radioisotope spike level, soil incubation period and extraction methods used to estimate the soil available P pool. On average, a spike level of 10–20 kBq g⁻¹ soil was used among studies but empirical assessments are required to confirm that this assumed range of spike level is sufficient to measure exchangeable P. We found that incubation duration should be ≤ 14 d because there is an increasing possibility of measuring declining cumulative gross P_min values beyond 14 d, even though a reduced cumulative pool with increasing time is theoretically impossible. Gross P_min rates were lower by IPD compared to IEK. However, 18 studies reported undetectable gross P_min, possibly due to the unverified but widely made assumption that biotic and abiotic process rates are additive. The complexity of the methodological issues may necessitate a more nuanced approach to select a method based on trade-offs. To address the methodological issues identified in this review, a greater quantity and quality of observations need to be collected (e.g., well-designed experiments, data quality assurance such as quenching correction).

预测土壤磷(P)的生物有效性需要了解有机磷矿化（Pmin），但评估Pmin率具有挑战性。使用放射性同位素P标记的最新进展使土壤中Pmin速率的估计成为可能。然而，放射性同位素稀释方法尚未标准化，这可能会影响研究结果的比较。我们进行了系统的文献检索，以(1)综合不同研究的不同程序，(2)比较两种最常用的方法，同位素交换动力学（IEK）和同位素池稀释（IPD）获得的土壤Pmin结果，以及(3)解决IEK和IPD的方法学优势和局限性。我们鉴定并分析了98项研究，发现在研究特定的放射性同位素峰值水平、土壤潜伏期和用于估计土壤有效磷库的提取方法方面存在很大差异。平均而言，研究中使用了10-20 kBq g-1土壤的峰值水平，但需要进行经验评估，以确认这个假设的峰值水平范围足以测量交换磷。我们发现，潜伏期应≤14天，因为在14天之后，测量累积总磷值下降的可能性越来越大，尽管理论上不可能在额外的时间内降低累积速率。与IEK相比，IPD的总保费较低。然而，18项研究报告了未检测到的总Pmin，可能是由于未经证实但广泛假设的生物和非生物过程速率是相加的。方法问题的复杂性需要通过先进的统计方法（例如，决策树）来选择基于权衡的方法。为了解决本综述中发现的方法学问题，需要收集更多数量和质量更高的观察结果（例如，精心设计的实验，淬火校正等数据质量保证）。

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引用次数: 0