Schnecker Jörg, Spiegel Felix, Li Yue, Richter Andreas, Sandén Taru, Spiegel Heide, Zechmeister-Boltenstern Sophie, Fuchslueger Lucia
Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria.
South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.
Biogeochemistry. 2023;164(3):521-535. doi: 10.1007/s10533-023-01050-x. Epub 2023 May 25.
In temperate, boreal and arctic soil systems, microbial biomass often increases during winter and decreases again in spring. This build-up and release of microbial carbon could potentially lead to a stabilization of soil carbon during winter times. Whether this increase is caused by changes in microbial physiology, in community composition, or by changed substrate allocation within microbes or communities is unclear. In a laboratory incubation study, we looked into microbial respiration and growth, as well as microbial glucose uptake and carbon resource partitioning in response to cooling. Soils taken from a temperate beech forest and temperate cropland system in October 2020, were cooled down from field temperature of 11 °C to 1 °C. We determined microbial growth using O-incorporation into DNA after the first two days of cooling and after an acclimation phase of 9 days; in addition, we traced C-labelled glucose into microbial biomass, CO respired from the soil, and into microbial phospholipid fatty acids (PLFAs). Our results show that the studied soil microbial communities responded strongly to soil cooling. The O data showed that growth and cell division were reduced when soils were cooled from 11 to 1 °C. Total respiration was also reduced but glucose uptake and glucose-derived respiration were unchanged. We found that microbes increased the investment of glucose-derived carbon in unsaturated phospholipid fatty acids at colder temperatures. Since unsaturated fatty acids retain fluidity at lower temperatures compared to saturated fatty acids, this could be interpreted as a precaution to reduced temperatures. Together with the maintained glucose uptake and reduced cell division, our findings show an immediate response of soil microorganisms to soil cooling, potentially to prepare for freezing events. The discrepancy between C uptake and cell division could explain previously observed high microbial biomass carbon in temperate soils in winter.
The online version contains supplementary material available at 10.1007/s10533-023-01050-x.
在温带、寒温带和北极土壤系统中，微生物生物量通常在冬季增加，春季又会再次减少。微生物碳的这种积累和释放可能会在冬季使土壤碳趋于稳定。目前尚不清楚这种增加是由微生物生理变化、群落组成变化，还是微生物或群落内底物分配变化引起的。在一项实验室培养研究中，我们研究了微生物呼吸与生长，以及微生物对冷却的葡萄糖摄取和碳资源分配情况。采集了2020年10月来自温带山毛榉林和温带农田系统的土壤，将其从11°C的田间温度冷却至1°C。在冷却的前两天以及9天的适应期后，我们通过将¹⁸O掺入DNA来测定微生物生长；此外，我们追踪了¹³C标记的葡萄糖在微生物生物量、从土壤中呼出的CO₂以及微生物磷脂脂肪酸（PLFA）中的去向。我们的结果表明，所研究的土壤微生物群落对土壤冷却反应强烈。¹⁸O数据显示，当土壤从11°C冷却至1°C时，生长和细胞分裂减少。总呼吸也减少，但葡萄糖摄取和源自葡萄糖的呼吸没有变化。我们发现，在较低温度下，微生物会增加源自葡萄糖的碳在不饱和磷脂脂肪酸中的投入。由于与饱和脂肪酸相比，不饱和脂肪酸在较低温度下能保持流动性，这可以解释为对低温的一种预防措施。连同维持的葡萄糖摄取和减少的细胞分裂，我们的研究结果表明土壤微生物对土壤冷却有即时反应，可能是为结冰事件做准备。碳摄取与细胞分裂之间的差异可以解释此前在温带土壤冬季观察到的高微生物生物量碳现象。
在线版本包含可在10.1007/s10533 - 023 - 01050 - x获取的补充材料。
