PDF(Pubmed)
Abstract：
Physiological responses of soil microorganisms to global warming are important for soil ecosystem function and the terrestrial carbon cycle. Here, we investigate the effects of weeks, years, and decades of soil warming across seasons and time on the microbial protein biosynthesis machineries (i.e. ribosomes), the most abundant cellular macromolecular complexes, using RNA:DNA and RNA:MBC (microbial biomass carbon) ratios as proxies for cellular ribosome contents. We compared warmed soils and non-warmed controls of 15 replicated subarctic grassland and forest soil temperature gradients subject to natural geothermal warming. RNA:DNA ratios tended to be lower in the warmed soils during summer and autumn, independent of warming duration (6 weeks, 8-14 years, and > 50 years), warming intensity (+3°C, +6°C, and +9°C), and ecosystem type. With increasing temperatures, RNA:MBC ratios were also decreasing. Additionally, seasonal RNA:DNA ratios of the consecutively sampled forest showed the same temperature-driven pattern. This suggests that subarctic soil microorganisms are depleted of ribosomes under warm conditions and the lack of consistent relationships with other physicochemical parameters besides temperature further suggests temperature as key driver. Furthermore, in incubation experiments, we measured significantly higher CO2 emission rates per unit of RNA from short- and long-term warmed soils compared to non-warmed controls. In conclusion, ribosome reduction may represent a widespread microbial physiological response to warming that offers a selective advantage at higher temperatures, as energy and matter can be reallocated from ribosome synthesis to other processes including substrate uptake and turnover. This way, ribosome reduction could have a substantial effect on soil carbon dynamics.
摘要：
土壤微生物对全球变暖的生理响应对土壤生态系统功能和陆地碳循环具有重要意义。这里,我们调查了几周的影响，年,和几十年的土壤变暖跨季节和时间的微生物蛋白质生物合成机制（即核糖体），最丰富的细胞大分子复合物，使用RNA：DNA和RNA：MBC（微生物生物质碳）比率作为细胞核糖体含量的代理。我们比较了受自然地热变暖影响的15个复制的亚北极草地和森林土壤温度梯度的温暖土壤和非温暖对照。在夏季和秋季，温暖的土壤中的RNA：DNA比率趋于较低，独立于变暖持续时间(6周，8-14年,>50年)，增温强度(+3°C，+6°C,+9°C),和生态系统类型。随着温度升高,RNA:MBC比率也降低。此外,连续采样森林的季节性RNA：DNA比率显示出相同的温度驱动模式。这表明，在温暖的条件下，亚北极土壤微生物的核糖体被耗尽，并且除温度外，与其他物理化学参数缺乏一致的关系进一步表明温度是关键驱动因素。此外，在孵化实验中，与未加温的对照相比，我们从短期和长期加温的土壤中测量到每单位RNA的CO2排放率显着提高。总之,核糖体减少可能代表了微生物对变暖的广泛生理反应，在较高温度下提供了选择性优势，因为能量和物质可以从核糖体合成重新分配到其他过程，包括底物摄取和周转。这边,核糖体的减少可能对土壤碳动力学产生重大影响。
