Microbial C:N:P stoichiometry and turnover depend on nutrients availability in soil: A 14C, 15N and 33P triple labelling study
Microbial C:N:P stoichiometry and turnover depend on nutrients availability in soil: A 14C, 15N and 33P triple labelling study
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DOI：
10.1016/j.soilbio.2019.01.017
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发表时间：
2019-04-01
影响因子：
9.7
通讯作者：
Kuzyakov, Yakov
中科院分区：
文献类型：
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作者：
Chen, Jie;Seven, Jasmin;Kuzyakov, Yakov
微生物生物量周转和相关的碳（C-mic），氮（N-mic）和磷（P-mic）的循环取决于它们的化学计量关系，并对土壤肥力起着至关重要的作用。研究了极低磷（Low-P）和高磷（High-P）森林土壤中C、N-MIC、P-MIC、微生物呼吸速率（CO2排放）和总DNA含量对C和养分添加的响应。低磷和高磷土壤都用低和高水平的C、N和P（5%和200%的C-MIC、N-MIC和P-MIC）处理。在添加C（C-14）和N（N-15）之前添加磷（P-33）以研究潜在的磷限制。我们假设微生物生物量C和营养物周转的两种模式：1）通过细胞内代谢维持和/或2）通过坏死物质再利用的微生物生长和死亡。在低磷土壤中，2天前增加的C-MIC和P-MIC相比，增加的CO2排放量和DNA含量高CN输入后，表明快速的初始吸收的C和限制养分进入微生物细胞。它还证明了在微生物生长开始之前的滞后期。然而，在高磷土壤中，CO2排放量和DNA含量的增加，同时增加的微生物生物量，反映了微生物的能力，立即增长。此后，CO2排放量和DNA含量均下降到添加CNP前的水平，低磷土壤的C-MIC和P-MIC下降，高磷土壤的C-MIC和P-MIC下降，表明低磷土壤存在C和P限制，高磷土壤存在N限制。在低CNP添加量下，高磷土壤微生物处于生长状态，而低磷土壤微生物主要处于维持状态。低磷土壤中维持的微生物在去除养分限制后可以切换到生长/死亡模式。高CNP输入导致低磷土壤中C-mic：N-mic：P-mic的化学计量比从691：105：1变化到33：1：1，这主要是由于微生物生物量中限制性元素（C和P）的储存量增加。在低CNP添加量下，由于维持时C和营养物质的内源性代谢，该比值保持稳定。微生物在生长/死亡模式下更快地周转C和营养物质，证实了生态学的一个关键原则：元素的限制越强，元素在生物体内的保留越有效，并且它被重新利用的程度越高。与C-MIC：N-MIC：P-MIC化学计量的三重标记方法有助于确定营养有限和无限土壤中微生物生物量CNP周转的主要维持和生长/死亡模式。
Microbial biomass turnover and the associated recycling of carbon (C-mic), nitrogen (N-mic) and phosphorus (P-mic) depend on their stoichiometric relationships and plays a pivotal role for soil fertility. This study examines the responses of C-mic, N-mic P-mic, the microbial respiration rate (CO2 efflux), and the total DNA content to C and nutrient addition in forest soils with very low (Low-P) and high P (High-P) contents. Both the Low-P and High-P soils were treated with a low and high level of C, N and P (5% and 200% of C-mic, N-mic and P-mic). Phosphorus (P-33) was added before the addition of C (C-14) and N (N-15) to investigate the potential P limitation. We hypothesized two modes of microbial biomass C and nutrient turnover: 1) maintenance through intracellular metabolisms and/or 2) microbial growth and death through necromass reutilization. In Low-P soil, the 2-day-sooner increase of C-mic and P-mic compared to the increase of CO2 efflux and DNA content after high CN input showed the rapid initial uptake of C and limiting nutrients into microbial cells. It also demonstrated a lag period before microbial growth commenced. In High-P soil, however, the CO2 efflux and DNA content increased simultaneously with increases in microbial biomass, reflecting the microbial capacity for immediate growth. Afterwards, CO2 efflux and DNA content dropped to the level before CNP addition, with a decline of C-mic and P-mic in Low-P soil and a decline of in High-P soil, suggesting a C and P limitation in Low-P soil and N limitation in High-P soil. Under low CNP addition, the microorganisms in High-P soil are ready to grow, while those in Low-P soil are mainly in maintenance mode. The microorganisms under maintenance in low-P soil can switch to growth/death mode after removing the nutrient limitation. High CNP input caused a non-homeostatic response of C-mic: N-mic: P-mic stoichiometry from 691:105:1 to 33:1:1 in Low-P soil, mainly resulting from a higher storage of the limiting elements (C and P) in microbial biomass. The ratio remained stable under low CNP addition due to the endogenous metabolism of C and nutrient at maintenance. The C and nutrient were turn-overed much faster by microorganisms in the growth/death mode, confirming a key principle of ecology: the stronger the limitation by an element, the more efficiently that element is retained within an organism, and the more intensively it is reused. The triple labeling approach linked with C-mic: N-mic: P-mic stoichiometry helped to identify the dominant maintenance and growth/death modes of microbial biomass CNP turnover in nutrient-limited and -unlimited soil.