Microbial growth and enzyme kinetics in rhizosphere hotspots are modulated by soil organics and nutrient availability

被引:100
作者
Tian, Peng [1 ,2 ]
Razavi, Bahar S. [3 ]
Zhang, Xuechen [4 ]
Wang, Qingkui [1 ,5 ]
Blagodatskaya, Evgenia [6 ,7 ]
机构
[1] Inst Appl Ecol, CAS Key Lab Forest Ecol & Management, Huitong Expt Stn Forest Ecol, Shenyang 110164, Liaoning, Peoples R China
[2] Univ Chinese Acad Sci, Beijing 100049, Peoples R China
[3] Univ Kiel, Inst Phytopathol, Dept Soil & Plant Microbiome, Kiel, Germany
[4] Univ Gottingen, Dept Biogeochem Agroecosyst, Gottingen, Germany
[5] Huitong Natl Res Stn Forest Ecosyst, Huitong 418307, Peoples R China
[6] UFZ Helmholtz Ctr Environm Res, Dept Soil Ecol, Halle, Saale, Germany
[7] Peoples Friendship Univ Russia RUDN Univ, Moscow 117198, Russia
基金
中国国家自然科学基金;
关键词
Microbial hotspots; Soil zymography; Microbial growth; Enzyme kinetics; ECOENZYMATIC STOICHIOMETRY; SPATIAL-DISTRIBUTION; HOT MOMENTS; DIVERSITY; MICROORGANISMS; ROOTS; MECHANISMS; LIMITATION; PARAMETERS; DYNAMICS;
D O I
10.1016/j.soilbio.2019.107662
中图分类号
S15 [土壤学];
学科分类号
0903 ; 090301 ;
摘要
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 (mu(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 mu(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 p-glucosidase and leucine aminopeptidase to the substrate was detected in the hotspots versus bulk soil, whereas only p-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, beta-glucosidase positively correlated with the biomass of actively growing microorganisms. The fertile soil, on the whole, showed greater limax 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.
引用
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页数:9
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