Over recent decades, there has been a noticeable change in vegetation diversity accompanied by increased plant productivity in tundra systems of the High-Arctic, leading to elevated carbon and nutrient inputs into the soil. This shift can alter microbial community composition and activity in these ecosystems. In this study, we aimed to identify genes transcribed by active microorganisms and compare their expression in unamended and amended soils with labile carbon and/or nitrogen compounds. We also assessed gene expression differences in tundra soils with varying edaphic characteristics (upslope vs. downslope sites). We amended soils with either glycine or cellulose or left them unamended (i.e., control) for 7 days of incubation, and we isolated and sequenced RNA using Illumina technology. Whereas we observed only a weak transcriptional response after cellulose addition, the glycine addition significantly influenced transcriptional patterns, with upregulation of carbon- and nitrogen-cycling genes. Notably, microbial taxa from the Pseudomonadaceae and Micrococcaceae families showed the most pronounced response to glycine, indicating a shift of the communities towards copiotrophic organisms. This response was consistent across the two soil types, suggesting a common impact on microbial community activity. These findings suggest that an increase in carbon and nitrogen inputs could substantially affect microbial functioning in High-Arctic tundra soils, with potential implications for ecosystem dynamics under global warming.

中文翻译：

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高北极苔原土壤微生物组对碳输入的宏转录组反应


近几十年来，高纬度北极苔原系统的植被多样性发生了显着变化，植物生产力也随之提高，导致土壤中的碳和养分输入增加。这种转变可以改变这些生态系统中的微生物群落组成和活动。在这项研究中，我们的目的是鉴定活性微生物转录的基因，并比较它们在含有不稳定碳和/或氮化合物的未改良和改良土壤中的表达。我们还评估了具有不同土壤特征（上坡与下坡地点）的苔原土壤中的基因表达差异。我们用甘氨酸或纤维素改良土壤，或将其不改良（即对照）培养 7 天，然后使用 Illumina 技术分离 RNA 并对其进行测序。虽然我们在添加纤维素后仅观察到微弱的转录反应，但甘氨酸的添加显着影响转录模式，并上调碳和氮循环基因。值得注意的是，来自假单胞菌科和微球菌科的微生物类群对甘氨酸表现出最明显的反应，表明群落向富营养生物体转变。这种反应在两种土壤类型中是一致的，表明对微生物群落活动有共同的影响。这些发现表明，碳和氮输入的增加可能会严重影响高北极苔原土壤中的微生物功能，并对全球变暖下的生态系统动态产生潜在影响。