Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China; Naiman Desertification Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Tongliao 028300, China.
Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China; Naiman Desertification Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Tongliao 028300, China.
Sci Total Environ. 2023 May 20;874:162504. doi: 10.1016/j.scitotenv.2023.162504. Epub 2023 Feb 28.
Soil extracellular enzyme activity (EEA) stoichiometry reflects the dynamic balance between microorganism metabolic demands for resources and nutrient availability. However, variations in metabolic limitations and their driving factors in arid desert areas with oligotrophic environments remain poorly understood. In this study, we investigated sites in different desert types in western China and measured the activities of two C-acquiring enzymes (β-1,4-glucosidase and β-D-cellobiohydrolase), two N-acquiring enzymes (β-1,4-N-acetylglucosaminidase and L-leucine aminopeptidase), and one organic-P-acquiring enzyme (alkaline phosphatase) to quantify and compare the metabolic limitations of soil microorganisms based on their EEA stoichiometry. The ratios of log-transformed C-, N-, and P-acquiring enzyme activities for all deserts combined were 1:1.1:0.9, which is close to the hypothetical global mean EEA stoichiometry (1:1:1). We quantified the microbial nutrient limitation by means of vector analysis using the proportional EEAs, and found that microbial metabolism was co-limited by soil C and N. For different desert types, the microbial N limitation increased in the following order: gravel desert < sand desert < mud desert < salt desert. Overall, the study area's climate explained the largest proportion of the variation in the microbial limitation (17.9 %), followed by soil abiotic factors (6.6 %) and biological factors (5.1 %). Our results confirmed that the EEA stoichiometry method can be used in microbial resource ecology research in a range of desert types, and that the soil microorganisms maintained community-level nutrient element homeostasis by adjusting enzyme production to increase uptake of scarce nutrients even in extremely oligotrophic environments such as deserts.
土壤胞外酶活性（EEA）化学计量反映了微生物代谢对资源的需求与养分供应之间的动态平衡。然而，在贫营养的干旱荒漠地区，微生物代谢限制及其驱动因素的变化仍知之甚少。本研究调查了中国西部不同荒漠类型的地点，并测量了两种 C 类获取酶（β-1,4-葡萄糖苷酶和β-D-纤维二糖水解酶）、两种 N 类获取酶（β-1,4-N-乙酰葡萄糖胺酶和 L-亮氨酸氨肽酶）和一种有机磷获取酶（碱性磷酸酶）的活性，以基于 EEA 化学计量来量化和比较土壤微生物的代谢限制。所有荒漠的 C、N 和 P 类获取酶活性的对数比为 1:1.1:0.9，接近于假设的全球平均 EEA 化学计量比（1:1:1）。我们通过使用比例 EEAs 的向量分析量化了微生物养分限制，并发现微生物代谢受到土壤 C 和 N 的共同限制。对于不同的荒漠类型，微生物 N 限制按以下顺序增加：砾漠<沙漠<泥漠<盐漠。总的来说，研究区域的气候解释了微生物限制变化的最大比例（17.9%），其次是土壤非生物因素（6.6%）和生物因素（5.1%）。我们的研究结果证实，EEA 化学计量法可用于研究各种荒漠类型的微生物资源生态学，土壤微生物通过调节酶的产生来增加对稀缺养分的吸收，从而维持社区水平的养分元素稳态，即使在荒漠等极其贫营养的环境中也是如此。
