Substrate quality affects microbial‐ and enzyme activities in rooted soil
Substrate quality affects microbial‐ and enzyme activities in rooted soil
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DOI：
10.1002/jpln.201400518
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发表时间：
2016-02
影响因子：
2.5
通讯作者：
S. Loeppmann;M. Semenov;E. Blagodatskaya;Y. Kuzyakov
中科院分区：
文献类型：
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作者：
S. Loeppmann;M. Semenov;E. Blagodatskaya;Y. Kuzyakov
根际是通过根沉积物反映高基质输入的土壤圈。活性微生物和胞外酶是土壤基质利用的重要因素，尤其是根际土壤。我们测试了可耕地土壤中的微生物和酶活性，以研究连续输入易获得的有机物（例如，根分泌物）到微生物群落。在玉米田间试验中，分析了根际土壤和无根土壤的微生物活性指标，如比微生物生长速率和6种水解性胞外酶（β-葡萄糖苷酶、β-纤维二糖水解酶、β-木糖苷酶、酸性磷酸酶、亮氨酸氨肽酶和酪氨酸氨肽酶）的动力学。更高的潜在活动的亮氨酸氨肽酶（2倍）的根与无根土壤表明酶的生产成本增加，这阻碍了特定的微生物生长速率。基质诱导呼吸法和dsDNA提取法测定的土壤微生物总生物量分别比无根土壤高23%和42%。在10-20 cm土层中，与表层相比，根际土壤中β-葡萄糖苷酶和酸性磷酸酶的活性分别降低了23%和25%，而β-纤维二糖水解酶的活性则提高了300%。在10-20 cm土层中，根系活跃生长的微生物生物量比上10 cm土层增加了17倍。尽管特定的微生物生长速率没有显示出变化的根的存在下，这些速率下降了42%，在10-20厘米的深度相比，表层。这表明，随着深度的增加，高度活跃但生长较慢的微生物丰度占主导地位，也反映了它们较慢的周转。微生物生长策略的转变、酶产量的上调和微生物呼吸作用的增加表明玉米种植土壤中存在强烈的根系效应。
The rhizosphere reflects a sphere of high substrate input by means of rhizodeposits. Active microorganisms and extracellular enzymes are known to be responsible for substrate utilization in soil, especially in rooted soil. We tested for microbial- and enzyme activities in arable soil, in order to investigate the effects of continuous input of easily available organics (e.g., root-exudates) to the microbial community. In a field experiment with maize, rooted and root-free soil were analyzed and rhizosphere processes were linked to microbial activity indicators such as specific microbial growth rates and kinetics of six hydrolytic extracellular enzymes: β-glucosidase, β-cellobiohydrolase, β-xylosidase, acid phosphatase, leucine- and tyrosine-aminopeptidase. Higher potential activities of leucine-aminopeptidase (2-fold) for rooted vs. root-free soil suggested increased costs of enzyme production, which retarded the specific microbial growth rates. Total microbial biomass determined by the substrate-induced respiration technique and dsDNA extraction method was 23% and 42% higher in the rooted surface-layer (0–10 cm) compared to the root-free soil, respectively. For the rooted soil, potential enzyme activities of β-glucosidase were reduced by 23% and acid phosphatase by 25%, and increased by 300% for β-cellobiohydrolase at 10–20 cm depth compared to the surface-layer. The actively growing microbial biomass increased by the 17-fold in rooted soil in the 10–20 cm layer compared to the upper 10 cm. Despite the specific microbial growth rates showing no changes in the presence of roots, these rates decreased by 42% at 10–20 cm depth compared to the surface-layer. This suggests the dominance in abundances of highly active but slower growing microbes with depth, reflecting also their slower turnover. Shifts in microbial growth strategy, upregulation of enzyme production and increased microbial respiration indicate strong root effects in maize planted soil.