The input of labile organics by plant roots stimulates microbial activity and therefore facilitates biochemical process rates in the rhizosphere compared to bulk soil, forming microbial hotspots. However, the extent to which the functional properties of soil microorganisms are different in the hotspots formed in soils with contrasting fertility remains unclear. We identified the hotspots related to different levels of Zea mays L. root architecture by zymography of leucine aminopeptidase in two soils with contrasting fertility. The hotspots localized by tiny wet-needle approach around first- and second-order roots were compared for parameters of microbial growth and enzyme kinetics. The pattern of hotspot distribution was more dispersed and the hotspot area was one order of magnitude smaller around first-versus second-order roots. The specific microbial growth rate (μ_m) and biomass of active microorganisms were soil-specific, with no difference between the hotspots and bulk soil in the fertile soil. In contrast, in the soil poor in organic matter and nutrients, 1.2-fold higher μ_m and greater growing biomass were found in the hotspots versus bulk soil. Lower enzyme affinity (1.3–2.2 times higher K_m value) of β-glucosidase and leucine aminopeptidase to the substrate was detected in the hotspots versus bulk soil, whereas only β-glucosidase showed higher potential enzyme activity (V_max) in the hotspots, being 1.7–2.1 times greater than that in bulk soil. Notably, the activity of C-acquiring enzyme, β-glucosidase positively correlated with the biomass of actively growing microorganisms. The fertile soil, on the whole, showed greater V_max and catalytic efficiency (V_max/K_m) and an approximately 2.5 times shorter substrate turnover time as compared to the poor soil. Therefore, we conclude that i) the differences in microbial growth strategy between rhizosphere hotspots and bulk soil were dependent on soil fertility; ii) affinity of hydrolytic enzyme systems to substrate was mainly modulated by plant, whereas potential enzymatic activity was driven by both plant and soil quality.

与块状土壤相比，植物根部输入的不稳定有机物刺激了微生物活动，因此促进了根际中生化过程的速率，从而形成了微生物热点。然而，在土壤肥力形成对比的热点地区，土壤微生物的功能特性在多大程度上尚不明确。我们确定了与玉米不同水平相关的热点L.通过亮氨酸氨肽酶的酶学分析在两种土壤中具有相反肥力的根系结构。比较了通过细湿针法定位在一阶和二阶根附近的热点的微生物生长和酶动力学参数。热点分布的模式更加分散，并且热点面积围绕一阶与二阶根部周围减小了一个数量级。活性微生物的比微生物生长速率（_μm）和生物量是特定于土壤的，肥沃土壤中的热点和块状土壤之间没有差异。相比之下，在有机质和养分贫乏的土壤中，热点地区的散布的_μm和生长的生物量却是散装土壤的1.2倍。较低的酶亲和力（较高的1.3–2.2倍与大块土壤相比，在热点地区检测到了β-葡萄糖苷酶和亮氨酸氨基肽酶的K _m值，而在热点地区，只有β-葡萄糖苷酶显示出更高的潜在酶活性（V _max），比在土壤中高1.7-2.1倍。散土。值得注意的是，C-获得酶，β-葡糖苷酶的活性与活跃生长的微生物的生物量正相关。总体而言，肥沃的土壤显示出更高的V _max和催化效率（V _max / K _m），与较贫瘠的土壤相比，底材周转时间缩短了约2.5倍。因此，我们得出以下结论：i）根际热点和散装土壤之间微生物生长策略的差异取决于土壤肥力；ii）水解酶系统对底物的亲和力主要受植物调节，而潜在的酶活性受植物和土壤质量的驱动。